一 How do you feel if you have the flu?

echam2022-10-04 11:39:541条回答

一 How do you feel if you have the flu?
一 _____
[ ]
A. I feel sad.
B. I feel excited.

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(一)直接引述别人的原话,叫做直接引语;用自己话转述别人的话,叫做间接引语.间接引语一般构成宾语从句.直接引语必须放在引号内,间接引语则不用引号.直接引语改为间接引语时,除将引语部分变成宾语从句外,还必须对直接引语中的人称、时态、指示代词、时间状语、地点状语等进行改变.
1.时态的变化:直接引语变为间接引语时,通常受转述动词said,asked等的影响而使用过去化的时态,即把原来的时态向过去推,也就是一般现在时变为一般过去时,现在进行时变为过去进行时,等等.例如:
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2.人称代词、指示代词、时间状语、地点状语等等的变化:根据意义进行相应的变化,例如:
She asked Jack,“Where have you been?”
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He said,“These books are mine.”
→He said that those books were his.
(二)直接引语改为间接引语时,都使用陈述语序,但是因为原句的句式不同,所以变成间接引语时所用的连词会有所不同.直接引语如果是一般疑问句,用连接词whether或if;如果是特殊疑问句,则用疑问词引导间接引语.转述的动词一般用asked,可以在其后加上一个间接宾语me,him,her,us等.如:
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“What do you do every Sunday?”My friend asked me.
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4.现在进行时 am/is/are + being + 过去分词
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His work has been finished.
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B:Oh,(3)w____ shall we have it?
A:We'll have it at 3:00 pm(4)o____Satueday afternoon.Please get your football shoes ready for the(5)g___.
B:Sure!Shall we ask Tom to(6)p____ with us?
A:Oh,dear!I forgot to(7)t___ you.He hurt his left arm and can't do any(8)s___.
B:I'm(9)s____ to hear that.Let's go to(10)s____him together now.
(1)_____ (2)_____ (3)_____ (4)______ (5)______(6)______(7)_____(8)_____(9)______(10)______急
tonkachen1年前4
qq11292007 共回答了17个问题 | 采纳率94.1%
1.something
2.about
3.when
4.on
5.game
6.play
7.tell
8.sports
9.sorry
see
Can help you?一 单项选择1._____loves his students very much.A.She
Can help you?
一 单项选择
1._____loves his students very much.A.She B.Him C.He D.Her
2.He can piay basketball very well ___ he can sing well.A.and B.too C.but D.to
二 中译英
1.让我来介绍一下我们英语俱乐部的一位新成员.
2.一起都好吗?
3.他是做什么工作的?
4.明天见.
huozibingh1年前1
lwanh 共回答了25个问题 | 采纳率96%
1 C 后面有his
2 A 并列关系
Let me introduce a new member in our English club to you
Is everything going on well?
What is he?/what does he do?
see you tomorrow
英语翻译一:Tailor The Computer System To Meet The Needs Of a Busi
英语翻译
一:Tailor The Computer System To Meet The Needs Of a Business.
二:It Would Be Rude To Remark On Her Appearance.
三:手机写不下字了!
jack13051年前4
一代新贵 共回答了17个问题 | 采纳率76.5%
1.调整计算机系统以满足业务需求.
2.对她的长相品头论足是不礼貌的.
3.There is no enough space for my cellphone to add any words.
必修一英语连接Dr bethune was born in Gravenhurst,Ontario,Canada.His
必修一英语连接Dr bethune was born in Gravenhurst,Ontario,Canada.His grandfat
grandfather was also a well-know doctor(whose)
入为声之骨1年前1
peter19832002 共回答了29个问题 | 采纳率86.2%
把".his"变成",whose"就行
一.连词句子1.play,the,I,guitar,can,.2.doesn't,a,blue,have,jacket,
一.连词句子1.play,the,I,guitar,can,.2.doesn't,a,blue,have,jacket,he,.3.in,drawer,the,are,keys,he,.4.she,to,a,movie,go,to,dose,want,5.what,weather,the,today,is,like,二.1.Open the window,please(改成否定句)2.I can see a bottle of water on the table.(对a bottle of water 做出提问)3.There are thirty students in the classroom.(对thirty做出提问)4.The often play football on the playground.(对on the playground做出提问)
绝尘恋1年前3
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1. I can play the guitar.
2 He doesn't have a blue jacket.
3 His keys are in the drawer.
4 Does she want to go to a movie?
5 What is the weather like today?
1. Don't open the window,Please.
2 What can you see on the table?
3. How many students are there in the classroom?
4 Where do they often play football?
生物必修一重点名词解释
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高中是不会考名词解释的。。。。
一缘起,天涯咫尺,一缘灭,咫尺天涯,
博客风采3361年前1
chenli1965 共回答了15个问题 | 采纳率100%
缘起,就算是天涯也不过咫尺间的距离,而若缘灭,咫尺之距也仿若天涯般遥远.
高一化学必修一知识总结
olidoran1年前1
amis123456 共回答了20个问题 | 采纳率90%
第一章 从实验学化学
一、常见物质的分离、提纯和鉴别
1.常用的物理方法——根据物质的物理性质上差异来分离.
混合物的物理分离方法
方法 适用范围 主要仪器 注意点 实例
固+液 蒸发 易溶固体与液体分开 酒精灯、蒸发皿、玻璃棒 ①不断搅拌;②最后用余热加热;③液体不超过容积2/3 NaCl(H2O)
固+固 结晶 溶解度差别大的溶质分开 NaCl(NaNO3)
升华 能升华固体与不升华物分开 酒精灯 I2(NaCl)
固+液 过滤 易溶物与难溶物分开 漏斗、烧杯 ①一角、二低、三碰;②沉淀要洗涤;③定量实验要“无损” NaCl(CaCO3)
液+液 萃取 溶质在互不相溶的溶剂里,溶解度的不同,把溶质分离出来 分液漏斗 ①先查漏;②对萃取剂的要求;③使漏斗内外大气相通;④上层液体从上口倒出 从溴水中提取Br2
分液 分离互不相溶液体 分液漏斗 乙酸乙酯与饱和Na2CO3溶液
蒸馏 分离沸点不同混合溶液 蒸馏烧瓶、冷凝管、温度计、牛角管 ①温度计水银球位于支管处;②冷凝水从下口通入;③加碎瓷片 乙醇和水、I2和CCl4
渗析 分离胶体与混在其中的分子、离子 半透膜 更换蒸馏水 淀粉与NaCl
盐析 加入某些盐,使溶质的溶解度降低而析出 烧杯 用固体盐或浓溶液 蛋白质溶液、硬脂酸钠和甘油
气+气 洗气 易溶气与难溶气分开 洗气瓶 长进短出 CO2(HCl)
液化 沸点不同气分开 U形管 常用冰水 NO2(N2O4)
i、蒸发和结晶 蒸发是将溶液浓缩、溶剂气化或溶质以晶体析出的方法.结晶是溶质从溶液中析出晶体的过程,可以用来分离和提纯几种可溶性固体的混合物.结晶的原理是根据混合物中各成分在某种溶剂里的溶解度的不同,通过蒸发减少溶剂或降低温度使溶解度变小,从而使晶体析出.加热蒸发皿使溶液蒸发时、要用玻璃棒不断搅动溶液,防止由于局部温度过高,造成液滴飞溅.当蒸发皿中出现较多的固体时,即停止加热,例如用结晶的方法分离NaCl和KNO3混合物.
ii、蒸馏 蒸馏是提纯或分离沸点不同的液体混合物的方法.用蒸馏原理进行多种混合液体的分离,叫分馏.
操作时要注意:
①在蒸馏烧瓶中放少量碎瓷片,防止液体暴沸.
②温度计水银球的位置应与支管底口下缘位于同一水平线上.
③蒸馏烧瓶中所盛放液体不能超过其容积的2/3,也不能少于l/3.
④冷凝管中冷却水从下口进,从上口出.
⑤加热温度不能超过混合物中沸点最高物质的沸点,例如用分馏的方法进行石油的分馏.
iii、分液和萃取 分液是把两种互不相溶、密度也不相同的液体分离开的方法.萃取是利用溶质在互不相溶的溶剂里的溶解度不同,用一种溶剂把溶质从它与另一种溶剂所组成的溶液中提取出来的方法.选择的萃取剂应符合下列要求:和原溶液中的溶剂互不相溶;对溶质的溶解度要远大于原溶剂,并且溶剂易挥发.
在萃取过程中要注意:
①将要萃取的溶液和萃取溶剂依次从上口倒入分液漏斗,其量不能超过漏斗容积的2/3,塞好塞子进行振荡.
②振荡时右手捏住漏斗上口的颈部,并用食指根部压紧塞子,以左手握住旋塞,同时用手指控制活塞,将漏斗倒转过来用力振荡.
③然后将分液漏斗静置,待液体分层后进行分液,分液时下层液体从漏斗口放出,上层液体从上口倒出.例如用四氯化碳萃取溴水里的溴.
iv、升华 升华是指固态物质吸热后不经过液态直接变成气态的过程.利用某些物质具有升华的特性,将这种物质和其它受热不升华的物质分离开来,例如加热使碘升华,来分离I2和SiO2的混合物.
2、化学方法分离和提纯物质
对物质的分离可一般先用化学方法对物质进行处理,然后再根据混合物的特点用恰当的分离方法(见化学基本操作)进行分离.
用化学方法分离和提纯物质时要注意:
①最好不引入新的杂质;
②不能损耗或减少被提纯物质的质量
③实验操作要简便,不能繁杂.用化学方法除去溶液中的杂质时,要使被分离的物质或离子尽可能除净,需要加入过量的分离试剂,在多步分离过程中,后加的试剂应能够把前面所加入的无关物质或离子除去.
对于无机物溶液常用下列方法进行分离和提纯:
(1)生成沉淀法 (2)生成气体法 (3)氧化还原法 (4)正盐和与酸式盐相互转化法 (5)利用物质的两性除去杂质 (6)离子交换法
常见物质除杂方法
序号 原物 所含杂质 除杂质试剂 主要操作方法
1 N2 O2 灼热的铜丝网 用固体转化气体
2 CO2 H2S CuSO4溶液 洗气
3 CO CO2 NaOH溶液 洗气
4 CO2 CO 灼热CuO 用固体转化气体
5 CO2 HCI 饱和的NaHCO3 洗气
6 H2S HCI 饱和的NaHS 洗气
7 SO2 HCI 饱和的NaHSO3 洗气
8 CI2 HCI 饱和的食盐水 洗气
9 CO2 SO2 饱和的NaHCO3 洗气
10 炭粉 MnO2 浓盐酸(需加热) 过滤
11 MnO2 C -------- 加热灼烧
12 炭粉 CuO 稀酸(如稀盐酸) 过滤
13 AI2O3 Fe2O3 NaOH(过量),CO2 过滤
14 Fe2O3 AI2O3 NaOH溶液 过滤
15 AI2O3 SiO2 盐酸`氨水 过滤
16 SiO2 ZnO HCI溶液 过滤,
17 BaSO4 BaCO3 HCI或稀H2SO4 过滤
18 NaHCO3溶液 Na2CO3 CO2 加酸转化法
19 NaCI溶液 NaHCO3 HCI 加酸转化法
20 FeCI3溶液 FeCI2 CI2 加氧化剂转化法
21 FeCI3溶液 CuCI2 Fe 、CI2 过滤
22 FeCI2溶液 FeCI3 Fe 加还原剂转化法
23 CuO Fe (磁铁) 吸附
24 Fe(OH)3胶体 FeCI3 蒸馏水 渗析
25 CuS FeS 稀盐酸 过滤
26 I2晶体 NaCI -------- 加热升华
27 NaCI晶体 NH4CL -------- 加热分解
28 KNO3晶体 NaCI 蒸馏水 重结晶.
3、物质的鉴别
物质的检验通常有鉴定、鉴别和推断三类,它们的共同点是:依据物质的特殊性质和特征反应,选择适当的试剂和方法,准确观察反应中的明显现象,如颜色的变化、沉淀的生成和溶解、气体的产生和气味、火焰的颜色等,进行判断、推理.
检验类型 鉴别 利用不同物质的性质差异,通过实验,将它们区别开来.
鉴定 根据物质的特性,通过实验,检验出该物质的成分,确定它是否是这种物质.
推断 根据已知实验及现象,分析判断,确定被检的是什么物质,并指出可能存在什么,不可能存在什么.
检验方法 ① 若是固体,一般应先用蒸馏水溶解
② 若同时检验多种物质,应将试管编号
③ 要取少量溶液放在试管中进行实验,绝不能在原试剂瓶中进行检验
④ 叙述顺序应是:实验(操作)→现象→结论→原理(写方程式)
① 常见气体的检验
常见气体 检验方法
氢气 纯净的氢气在空气中燃烧呈淡蓝色火焰,混合空气点燃有爆鸣声,生成物只有水.不是只有氢气才产生爆鸣声;可点燃的气体不一定是氢气
氧气 可使带火星的木条复燃
氯气 黄绿色,能使湿润的碘化钾淀粉试纸变蓝(O3、NO2也能使湿润的碘化钾淀粉试纸变蓝)
氯化氢 无色有刺激性气味的气体.在潮湿的空气中形成白雾,能使湿润的蓝色石蓝试纸变红;用蘸有浓氨水的玻璃棒靠近时冒白烟;将气体通入AgNO3溶液时有白色沉淀生成.
二氧化硫 无色有刺激性气味的气体.能使品红溶液褪色,加热后又显红色.能使酸性高锰酸钾溶液褪色.
硫化氢 无色有具鸡蛋气味的气体.能使Pb(NO3)2或CuSO4溶液产生黑色沉淀,或使湿润的醋酸铅试纸变黑.
氨气 无色有刺激性气味,能使湿润的红色石蕊试纸变蓝,用蘸有浓盐酸的玻璃棒靠近时能生成白烟.
二氧化氮 红棕色气体,通入水中生成无色的溶液并产生无色气体,水溶液显酸性.
一氧化氮 无色气体,在空气中立即变成红棕色
二氧化碳 能使澄清石灰水变浑浊;能使燃着的木条熄灭.SO2气体也能使澄清的石灰水变混浊,N2等气体也能使燃着的木条熄灭.
一氧化碳 可燃烧,火焰呈淡蓝色,燃烧后只生成CO2;能使灼热的CuO由黑色变成红色.
② 几种重要阳离子的检验
(l)H+ 能使紫色石蕊试液或橙色的甲基橙试液变为红色.
(2)Na+、K+ 用焰色反应来检验时,它们的火焰分别呈黄色、浅紫色(通过钴玻片).
(3)Ba2+ 能使稀硫酸或可溶性硫酸盐溶液产生白色BaSO4沉淀,且沉淀不溶于稀硝酸.
(4)Mg2+ 能与NaOH溶液反应生成白色Mg(OH)2沉淀,该沉淀能溶于NH4Cl溶液.
(5)Al3+ 能与适量的NaOH溶液反应生成白色Al(OH)3絮状沉淀,该沉淀能溶于盐酸或过量的NaOH溶液.
(6)Ag+ 能与稀盐酸或可溶性盐酸盐反应,生成白色AgCl沉淀,不溶于稀 HNO3,但溶于氨水,生成〔Ag(NH3)2〕+.
(7)NH4+ 铵盐(或浓溶液)与NaOH浓溶液反应,并加热,放出使湿润的红色石蓝试纸变蓝的有刺激性气味NH3气体.
(8)Fe2+ 能与少量NaOH溶液反应,先生成白色Fe(OH)2沉淀,迅速变成灰绿色,最后变成红褐色Fe(OH)3沉淀.或向亚铁盐的溶液里加入KSCN溶液,不显红色,加入少量新制的氯水后,立即显红色.2Fe2++Cl2=2Fe3++2Cl-
(9) Fe3+ 能与 KSCN溶液反应,变成血红色 Fe(SCN)3溶液,能与 NaOH溶液反应,生成红褐色Fe(OH)3沉淀.
(10)Cu2+ 蓝色水溶液(浓的CuCl2溶液显绿色),能与NaOH溶液反应,生成蓝色的Cu(OH)2沉淀,加热后可转变为黑色的 CuO沉淀.含Cu2+溶液能与Fe、Zn片等反应,在金属片上有红色的铜生成.
③ 几种重要的阴离子的检验
(1)OH- 能使无色酚酞、紫色石蕊、橙色的甲基橙等指示剂分别变为红色、蓝色、黄色.
(2)Cl- 能与硝酸银反应,生成白色的AgCl沉淀,沉淀不溶于稀硝酸,能溶于氨水,生成[Ag(NH3)2]+.
(3)Br- 能与硝酸银反应,生成淡黄色AgBr沉淀,不溶于稀硝酸.
(4)I- 能与硝酸银反应,生成黄色AgI沉淀,不溶于稀硝酸;也能与氯水反应,生成I2,使淀粉溶液变蓝.
(5)SO42- 能与含Ba2+溶液反应,生成白色BaSO4沉淀,不溶于硝酸.
(6)SO32- 浓溶液能与强酸反应,产生无色有刺激性气味的SO2气体,该气体能使品红溶液褪色.能与BaCl2溶液反应,生成白色BaSO3沉淀,该沉淀溶于盐酸,生成无色有刺激性气味的SO2气体.
(7)S2- 能与Pb(NO3)2溶液反应,生成黑色的PbS沉淀.
(8)CO32- 能与BaCl2溶液反应,生成白色的BaCO3沉淀,该沉淀溶于硝酸(或盐酸),生成无色无味、能使澄清石灰水变浑浊的CO2气体.
(9)HCO3- 取含HCO3-盐溶液煮沸,放出无色无味CO2气体,气体能使澄清石灰水变浑浊或向HCO3-盐酸溶液里加入稀MgSO4溶液,无现象,加热煮沸,有白色沉淀 MgCO3生成,同时放出 CO2气体.
(10)PO43- 含磷酸根的中性溶液,能与AgNO3反应,生成黄色Ag3PO4沉淀,该沉淀溶于硝酸.
(11)NO3- 浓溶液或晶体中加入铜片、浓硫酸加热,放出红棕色气体.
二、常见事故的处理
事故 处理方法
酒精及其它易燃有机物小面积失火 立即用湿布扑盖
钠、磷等失火 迅速用砂覆盖
少量酸(或碱)滴到桌上 立即用湿布擦净,再用水冲洗
较多量酸(或碱)流到桌上 立即用适量NaHCO3溶液(或稀HAC)作用,后用水冲洗
酸沾到皮肤或衣物上 先用抹布擦试,后用水冲洗,再用NaHCO3稀溶液冲洗
碱液沾到皮肤上 先用较多水冲洗,再用硼酸溶液洗
酸、碱溅在眼中 立即用水反复冲洗,并不断眨眼
苯酚沾到皮肤上 用酒精擦洗后用水冲洗
白磷沾到皮肤上 用CuSO4溶液洗伤口,后用稀KMnO4溶液湿敷
溴滴到皮肤上 应立即擦去,再用稀酒精等无毒有机溶济洗去,后涂硼酸、凡士林
误食重金属盐 应立即口服蛋清或生牛奶
汞滴落在桌上或地上 应立即撒上硫粉
三、化学计量
①物质的量
定义:表示一定数目微粒的集合体 符号n 单位 摩尔 符号 mol
阿伏加德罗常数:0.012kgC-12中所含有的碳原子数.用NA表示. 约为6.02x1023
微粒与物质的量
公式:n=
②摩尔质量:单位物质的量的物质所具有的质量 用M表示 单位:g/mol 数值上等于该物质的分子量
质量与物质的量
公式:n=
③物质的体积决定:①微粒的数目②微粒的大小③微粒间的距离
微粒的数目一定 固体液体主要决定②微粒的大小
气体主要决定③微粒间的距离
体积与物质的量
公式:n=
标准状况下 ,1mol任何气体的体积都约为22.4L
④阿伏加德罗定律:同温同压下, 相同体积的任何气体都含有相同的分子数
⑤物质的量浓度:单位体积溶液中所含溶质B的物质的量.符号CB 单位:mol/l
公式:CB=nB/V nB=CB×V V=nB/CB
溶液稀释规律 C(浓)×V(浓)=C(稀)×V(稀)
⑥ 溶液的配置
(l)配制溶质质量分数一定的溶液
计算:算出所需溶质和水的质量.把水的质量换算成体积.如溶质是液体时,要算出液体的体积.
称量:用天平称取固体溶质的质量;用量简量取所需液体、水的体积.
溶将固体或液体溶质倒入烧杯里,加入所需的水,用玻璃棒搅拌使溶质完全溶解.
(2)配制一定物质的量浓度的溶液 (配制前要检查容量瓶是否漏水)

计算:算出固体溶质的质量或液体溶质的体积.
称量:用托盘天平称取固体溶质质量,用量简量取所需液体溶质的体积.
溶将固体或液体溶质倒入烧杯中,加入适量的蒸馏水(约为所配溶液体积的1/6),用玻璃棒搅拌使之溶解,冷却到室温后,将溶液引流注入容量瓶里.
洗涤(转移):用适量蒸馏水将烧杯及玻璃棒洗涤2-3次,将洗涤液注入容量瓶.振荡,使溶液混合均匀.
定容:继续往容量瓶中小心地加水,直到液面接近刻度2-3mm处,改用胶头滴管加水,使溶液凹面恰好与刻度相切.把容量瓶盖紧,再振荡摇匀.
5、过滤 过滤是除去溶液里混有不溶于溶剂的杂质的方法.
过滤时应注意:①一贴:将滤纸折叠好放入漏斗,加少量蒸馏水润湿,使滤纸紧贴漏斗内壁.
②二低:滤纸边缘应略低于漏斗边缘,加入漏斗中液体的液面应略低于滤纸的边缘.
③三靠:向漏斗中倾倒液体时,烧杯的夹嘴应与玻璃棒接触;玻璃棒的底端应和过滤器有三层滤纸处轻轻接触;漏斗颈的末端应与接受器的内壁相接触,例如用过滤法除去粗食盐中少量的泥沙.
第二章 化学物质及其变化
一、物质的分类 金属:Na、Mg、Al
单质
非金属:S、O、N
酸性氧化物:SO3、SO2、P2O5等
氧化物 碱性氧化物:Na2O、CaO、Fe2O3
氧化物:Al2O3等
纯 盐氧化物:CO、NO等
净 含氧酸:HNO3、H2SO4等
物 按酸根分
无氧酸:HCl
强酸:HNO3、H2SO4 、HCl
酸 按强弱分
弱酸:H2CO3、HClO、CH3COOH
化 一元酸:HCl、HNO3
合 按电离出的H+数分 二元酸:H2SO4、H2SO3
物 多元酸:H3PO4
强碱:NaOH、Ba(OH)2
物 按强弱分
质 弱碱:NH3•H2O、Fe(OH)3

一元碱:NaOH、
按电离出的HO-数分 二元碱:Ba(OH)2
多元碱:Fe(OH)3
正盐:Na2CO3
盐 酸式盐:NaHCO3
碱式盐:Cu2(OH)2CO3
溶液:NaCl溶液、稀H2SO4等
混 悬浊液:泥水混合物等
合 乳浊液:油水混合物
物 胶体:Fe(OH)3胶体、淀粉溶液、烟、雾、有色玻璃等
二、分散系相关概念
1. 分散系:一种物质(或几种物质)以粒子形式分散到另一种物质里所形成的混合物,统称为分散系.
2. 分散质:分散系中分散成粒子的物质.
3. 分散剂:分散质分散在其中的物质.
4、分散系的分类:当分散剂是水或其他液体时,如果按照分散质粒子的大小来分类,可以把分散系分为:溶液、胶体和浊液.分散质粒子直径小于1nm的分散系叫溶液,在1nm-100nm之间的分散系称为胶体,而分散质粒子直径大于100nm的分散系叫做浊液.
下面比较几种分散系的不同:
分散系 溶 液 胶 体 浊 液
分散质的直径 <1nm(粒子直径小于10-9m) 1nm-100nm(粒子直径在10-9 ~ 10-7m) >100nm(粒子直径大于10-7m)
分散质粒子 单个小分子或离子 许多小分子集合体或高分子 巨大数目的分子集合体
实例 溶液酒精、氯化钠等 淀粉胶体、氢氧化铁胶体等 石灰乳、油水等

质 外观 均一、透明 均一、透明 不均一、不透明
稳定性 稳定 较稳定 不稳定
能否透过滤纸 能 能 不能
能否透过半透膜 能 不能 不能
鉴别 无丁达尔效应 有丁达尔效应 静置分层
注意:三种分散系的本质区别:分散质粒子的大小不同.
三、胶体
1、胶体的定义:分散质粒子直径大小在10-9~10-7m之间的分散系.
2、胶体的分类:
①. 根据分散质微粒组成的状况分类:
如: 胶体胶粒是由许多 等小分子聚集一起形成的微粒,其直径在1nm~100nm之间,这样的胶体叫粒子胶体. 又如:淀粉属高分子化合物,其单个分子的直径在1nm~100nm范围之内,这样的胶体叫分子胶体.
②. 根据分散剂的状态划分:
如:烟、云、雾等的分散剂为气体,这样的胶体叫做气溶胶;AgI溶胶、 溶胶、 溶胶,其分散剂为水,分散剂为液体的胶体叫做液溶胶;有色玻璃、烟水晶均以固体为分散剂,这样的胶体叫做固溶胶.
3、胶体的制备
A. 物理方法
① 机械法:利用机械磨碎法将固体颗粒直接磨成胶粒的大小
② 溶解法:利用高分子化合物分散在合适的溶剂中形成胶体,如蛋白质溶于水,淀粉溶于水、聚乙烯熔于某有机溶剂等.
B. 化学方法
① 水解促进法:FeCl3+3H2O(沸)= (胶体)+3HCl
② 复分解反应法:KI+AgNO3=AgI(胶体)+KNO3 Na2SiO3+2HCl=H2SiO3(胶体)+2NaCl
思考:若上述两种反应物的量均为大量,则可观察到什么现象?如何表达对应的两个反应方程式?提示:KI+AgNO3=AgI↓+KNO3(黄色↓)Na2SiO3+2HCl=H2SiO3↓+2NaCl(白色↓)
4、胶体的性质:
① 丁达尔效应——丁达尔效应是粒子对光散射作用的结果,是一种物理现象.丁达尔现象产生的原因,是因为胶体微粒直径大小恰当,当光照射胶粒上时,胶粒将光从各个方面全部反射,胶粒即成一小光源(这一现象叫光的散射),故可明显地看到由无数小光源形成的光亮“通路”.当光照在比较大或小的颗粒或微粒上则无此现象,只发生反射或将光全部吸收的现象,而以溶液和浊液无丁达尔现象,所以丁达尔效应常用于鉴别胶体和其他分散系.
② 布朗运动——在胶体中,由于胶粒在各个方向所受的力不能相互平衡而产生的无规则的运动,称为布朗运动.是胶体稳定的原因之一.
③ 电泳——在外加电场的作用下,胶体的微粒在分散剂里向阴极(或阳极)作定向移动的现象.胶体具有稳定性的重要原因是同一种胶粒带有同种电荷,相互排斥,另外,胶粒在分散力作用下作不停的无规则运动,使其受重力的影响有较大减弱,两者都使其不易聚集,从而使胶体较稳定.
说明:A、电泳现象表明胶粒带电荷,但胶体都是电中性的.胶粒带电的原因:胶体中单个胶粒的体积小,因而胶体中胶粒的表面积大,因而具备吸附能力.有的胶体中的胶粒吸附溶液中的阳离子而带正电;有的则吸附阴离子而带负电胶体的提纯,可采用渗析法来提纯胶体.使分子或离子通过半透膜从胶体里分离出去的操作方法叫渗析法.其原理是胶体粒子不能透过半透膜,而分子和离子可以透过半透膜.但胶体粒子可以透过滤纸,故不能用滤纸提纯胶体.
B、在此要熟悉常见胶体的胶粒所带电性,便于判断和分析一些实际问题.
带正电的胶粒胶体:金属氢氧化物如 、 胶体、金属氧化物.
带负电的胶粒胶体:非金属氧化物、金属硫化物As2S3胶体、硅酸胶体、土壤胶体
特殊:AgI胶粒随着AgNO3和KI相对量不同,而可带正电或负电.若KI过量,则AgI胶粒吸附较多I-而带负电;若AgNO3过量,则因吸附较多Ag+而带正电.当然,胶体中胶粒带电的电荷种类可能与其他因素有关.
C、同种胶体的胶粒带相同的电荷.
D、固溶胶不发生电泳现象.凡是胶粒带电荷的液溶胶,通常都可发生电泳现象.气溶胶在高压电的条件也能发生电泳现象.
胶体根据分散质微粒组成可分为粒子胶体(如 胶体,AgI胶体等)和分子胶体[如淀粉溶液,蛋白质溶液(习惯仍称其溶液,其实分散质微粒直径已达胶体范围),只有粒子胶体的胶粒带电荷,故可产生电泳现象.整个胶体仍呈电中性,所以在外电场作用下作定向移动的是胶粒而非胶体.
④聚沉——胶体分散系中,分散系微粒相互聚集而下沉的现象称为胶体的聚沉.能促使溶胶聚沉的外因有加电解质(酸、碱及盐)、加热、溶胶浓度增大、加胶粒带相反电荷的胶体等.有时胶体在凝聚时,会连同分散剂一道凝结成冻状物质,这种冻状物质叫凝胶.
胶体稳定存在的原因:(1)胶粒小,可被溶剂分子冲击不停地运动,不易下沉或上浮(2)胶粒带同性电荷,同性排斥,不易聚大,因而不下沉或上浮
胶体凝聚的方法:
(1)加入电解质:电解质电离出的阴、阳离子与胶粒所带的电荷发生电性中和,使胶粒间的排斥力下降,胶粒相互结合,导致颗粒直径>10-7m,从而沉降.
能力:离子电荷数,离子半径
阳离子使带负电荷胶粒的胶体凝聚的能力顺序为:Al3+>Fe3+>H+>Mg2+>Na+
阴离子使带正电荷胶粒的胶体凝聚的能力顺序为:SO42->NO3->Cl-
(2)加入带异性电荷胶粒的胶体:(3)加热、光照或射线等:加热可加快胶粒运动速率,增大胶粒之间的碰撞机会.如蛋白质溶液加热,较长时间光照都可使其凝聚甚至变性.
5、胶体的应用
胶体的知识在生活、生产和科研等方面有着重要用途,如常见的有:
① 盐卤点豆腐:将盐卤( )或石膏( )溶液加入豆浆中,使豆腐中的蛋白质和水等物质一起凝聚形成凝胶.
② 肥皂的制取分离 ③ 明矾、 溶液净水④ FeCl3溶液用于伤口止血 ⑤ 江河入海口形成的沙洲⑥ 水泥硬化 ⑦冶金厂大量烟尘用高压电除去⑧ 土壤胶体中离子的吸附和交换过程,保肥作用
⑨ 硅胶的制备: 含水4%的 叫硅胶
⑩ 用同一钢笔灌不同牌号墨水易发生堵塞
四、离子反应
1、电离 ( ionization )
电离:电解质溶于水或受热熔化时解离成自由离子的过程.
酸、碱、盐的水溶液可以导电,说明他们可以电离出自由移动的离子.不仅如此,酸、碱、盐等在熔融状态下也能电离而导电,于是我们依据这个性质把能够在水溶液里或熔融状态下能导电的化合物统称为电解质.
2、电离方程式
H2SO4 = 2H+ + SO42- HCl = H+ + Cl- HNO3 = H+ + NO3-
硫酸在水中电离生成了两个氢离子和一个硫酸根离子.盐酸,电离出一个氢离子和一个氯离子.硝酸则电离出一个氢离子和一个硝酸根离子.电离时生成的阳离子全部都是氢离子的化合物我们就称之为酸.从电离的角度,我们可以对酸的本质有一个新的认识.那碱还有盐又应怎么来定义呢?
电离时生成的阴离子全部都是氢氧根离子的化合物叫做碱.
电离时生成的金属阳离子(或NH4+)和酸根阴离子的化合物叫做盐.
书写下列物质的电离方程式:KCl、NaHSO4、NaHCO3
KCl == K+ + Cl― NaHSO4 == Na+ + H+ +SO42― NaHCO3 == Na+ + HCO3―
这里大家要特别注意,碳酸是一种弱酸,弱酸的酸式盐如碳酸氢钠在水溶液中主要是电离出钠离子还有碳酸氢根离子;而硫酸是强酸,其酸式盐就在水中则完全电离出钠离子,氢离子还有硫酸根离子.
〔小结〕注意:1、 HCO3-、OH-、SO42-等原子团不能拆开
2、HSO4―在水溶液中拆开写,在熔融状态下不拆开写.
3、电解质与非电解质
①电解质:在水溶液里或熔化状态下能够导电的化合物,如酸、碱、盐等.
②非电解质:在水溶液里和熔融状态下都不导电的化合物,如蔗糖、酒精等.
小结
(1)、能够导电的物质不一定全是电解质.
(2)、电解质必须在水溶液里或熔化状态下才能有自由移动的离子.
(3)、电解质和非电解质都是化合物,单质既不是电解也不是非电解质.
(4)、溶于水或熔化状态;注意:“或”字
(5)、溶于水和熔化状态两各条件只需满足其中之一,溶于水不是指和水反应;
(6)、化合物,电解质和非电解质,对于不是化合物的物质既不是电解质也不是非电解质.
4、电解质与电解质溶液的区别:
电解质是纯净物,电解质溶液是混合物.无论电解质还是非电解质的导电都是指本身,而不是说只要在水溶液或者是熔化能导电就是电解质.5、强电解质:在水溶液里全部电离成离子的电解质.
6、弱电解质:在水溶液里只有一部分分子电离成离子的电解质.
强、弱电解质对比
强电解质 弱电解质
物质结构 离子化合物,某些共价化合物 某些共价化合物
电离程度 完全 部分
溶液时微粒 水合离子 分子、水合离子
导电性 强 弱
物质类别实例 大多数盐类、强酸、强碱 弱酸、弱碱、水
8、离子方程式的书写• 第一步:写(基础) 写出正确的化学方程式
第二步:拆(关键) 把易溶、易电离的物质拆成离子形式(难溶、难电离的以及气体等仍用化学式表示) 第三步:删(途径)
删去两边不参加反应的离子第四步:查(保证)检查(质量守恒、电荷守恒)
※离子方程式的书写注意事项:
1.非电解质、弱电解质、难溶于水的物质,气体在反应物、生成物中出现,均写成化学式或分式.2.固体间的反应,即使是电解质,也写成化学式或分子式.
3.氧化物在反应物中、生成物中均写成化学式或分子式.4.浓H2SO4作为反应物和固体反应时,浓H2SO4写成化学式.5金属、非金属单质,无论在反应物、生成物中均写成化学式.微溶物作为反应物时,处于澄清溶液中时写成离子形式;处于浊液或固体时写成化学式.
一英语填空more and more middle school students are all _______ __
一英语填空
more and more middle school students are all _______ _______(追求时尚)
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following fashion
一.补全单词1.aff_ _d 2.dep_sit 3.inst_ _m_ _t 4.million_ _ _e5.in
一.补全单词
1.aff_ _d 2.dep_sit 3.inst_ _m_ _t 4.million_ _ _e
5.inst_ _d 6.exp_ _sive 7.pr_ _e 8.pre_ _y 9.co_ _ect
10.p_ _nd
二.写出所给单词的比较级和最高级(先写比较级)
1.expensive _________ _________
2.sharp _________ _________
3.interesting _________ _________
4.difficult _________ _________
5.smart _________ _________
三.汉译英
1.这是我曾经看过的最没意思的书.
____________________________________.
2.这种型号的没有价格贵的好.
___________________________________.
3.你可以先付50英镑定金,然后每月付16英镑,4年付清.
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1.afford
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3.installment
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5.instead
6.expensive
7.prove (有很多字都是pr__e)
8.pretty
9.correct
1.expensive,more expensive,most expensive
2.sharp,sharper,sharpest
3.interesting,more interesting,most interesting
4.difficult,more difficult,most difficult
5.smart,smarter,smartest
1.This is the least interesting book I have ever read.
2.This model is not as good as the more expensive one.
3.You can put 50 pounds as deposit first,then pay installments for 4 years,16 pounds per month.
初一英语作文 M一 plan
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璀璨星泪 共回答了17个问题 | 采纳率82.4%
My plan of visiting the moon
I'm so lucky that I have got an opportunity to visit the moon recently. I've planned to get to the back of the moon, and find out whether the alien has ever lived there or not. Besides, I'll take lots of pictures and appreciate the beauty of the earth from the moon. It will be an exciting tirp, isn't it ?
英语翻译The TV programs are subject to change without notice.翻译一
英语翻译
The TV programs are subject to change without notice.
翻译一下这句话,并告诉我这里的be subject
hjl6391年前4
g45h3 共回答了11个问题 | 采纳率90.9%
subject to
易受 ...影响的,屈服于 ...的,让步于 ...
这句话的意思是“电视节目如有变更,恕不另行通知”
一 ,根据提示写出单词 1.You can learn about other places ar
一 ,根据提示写出单词 1.You can learn about other places ar
一 ,根据提示写出单词
1.You can learn about other places around the world______
lsun2111年前1
落泊天使 共回答了15个问题 | 采纳率93.3%
到底是1根据提示,还是2在横线上填空呢?
1geography
2itself
高一物理必修一课后习题答案
我为黎狂1年前1
asdwKJRGSRTH 共回答了22个问题 | 采纳率81.8%
你能把题目发出来么
一,已知A={x|2^x=0.5},函数f(x)=log2(x/2)*logx(1/2).
一,已知A={x|2^x=0.5},函数f(x)=log2(x/2)*logx(1/2).
1)求A与B的交集.
2)记A交B=C,若函数y=f(x)的定义域为C,求函数的最大最小值.
二,已知4^x-9*2^(x+1)+32
落落无水1年前2
horace 共回答了22个问题 | 采纳率95.5%
不知道你是几年级学生,如果预习当中碰到这样的题完全可以学了以后再做,如果你已经上完了高一,那我不可能一步步给你推导的,于你于我都没什么益处,OK?
一、A可以解得是﹛x|x=√2},
所以C=[√2,8]
所以f(x)定义域为…
利用对数运算法则,f(x)=[log2(x)-log2(2)]*[log2(1)-logx(2)]
=logx(2)-1
因为定义域为…,所以logx(2)取值在[1/3,2]上
所以f(x)最大值为1,最小值为-2/3
二、先用换元整理不等式:
设t=2^x,则t≥0
则t^2-18t+32≤0
解得t∈[2,16]
则x∈[1,4]
整理函数式:
y=log1/2(x/2)* [log1/2(x/2)+log1/2(1/4)]
=[log1/2(x/2)]²+2log1/2(x/2)
换元:设m=log1/2(x/2),m∈[-1,1]
则y=m²+2m
利用二次函数知识得最大值为3,最小值为-1
三、【首先声明我不确定我的答案正确与否,但思路应该没有问题.】
先求得对称轴为x=1
①若m<n≤1
由图像性质,f(m)=-1/2m^2+m=2m
f(n)=-1/2n^2+n=2n
解得m=-2,n=0.
②若m<1<n,
则f(1)=2n,n=-1/4舍去
③若1≤m<n,
则f(m)=-1/2m^2+m=2n
f(n)=-1/2n^2+n=2m
解得m,n一个是4,一个是-2,舍去
综上所述,存在这样的实数m=-2,n=0满足上述题意.
一.选择填空 1.In the__,the tree's shadow is long. a.morning b.aft
一.选择填空 1.In the__,the tree's shadow is long. a.morning b.afternoon c.noon
2.Jack__his father.They have both big eyes. a.likes b.like c.is like
3.The moon__in the morning. a.goes up b.goes down c.rises
4.Four brothers are__blind. a.both b.all c.other
5.Enjoy__in the swimming class. a.yourself b.you c.youself
6.I need___,___and__for a swimming class.
a.a swimsuit, a swim cap, a pair of swim goggles
b.a swimsuit, a swimming cap, a pair of swimming goggles
c.a swimming suit, a swimming cap, a pair of swimming goggles
7.ls there__milk box on the table.
a./ b.any c.a
yyqshi1年前1
xiao肖茜xi 共回答了19个问题 | 采纳率84.2%
傍晚的时候,树影会变长,ok
英语翻译一- DAmericans usually make allowance for non-native spea
英语翻译
一- D
Americans usually make allowance for non-native speakers who have some trouble understanding english.But they become annoyed when a person preends to understand but doesn’t really and then creates problems because of misunderstanding what is said .Mo one wants soap when he asks for soup.So if you don’t understand what is said to you ,admit it and politely ask the person to repeat or explain.
Second,it is quite rude to converse with a compainion in your native language and leave your American friends standing there feeling stupid because they can’t understand the conversation.The Americans may also feel that you are talking about them or saying something you don’t want them to hear.If you must switch to yur native language to explain something to a non-English-speaking companion,at least translate for your American friends so they don’t feel left out.
Learn just a few more polite English expressions,and you’ll be ready to face the world of Americans with confidence.The polite response to a conpliment about your looks or your work is “Thank you”.(A smile and a nod is not enough.)The response to “Thank you” is ,of course,“You’re welcom.” If someone asks,“How are you ”,don’t give your medical history.Just say,“Fine,thanks,How are you?” Finally,what should you say when someone sneezes It may not seem logical,but the correct response is “God bless you .”thatVs about all there is to it.Now that you’re learned this general knowledge of manners in the U.S.A.,you’re ready to e polite in English.Let’s hope your American friends will be just as polite.
63008321年前1
yake35 共回答了15个问题 | 采纳率93.3%
美国人通常对非本地语言者不能很好理解英文比较宽容.但是如果一个人假装自己听懂了实际没有听懂,由此引发问题,他们就会比较苦恼.没有人希望点汤的时候拿上来的是肥皂(英文中“汤”和“肥皂”发音相近).所以,如果你没听懂跟你说的话,你就承认自己没听懂然后礼貌地请求对方再说一遍或者解释一下.
第二,情况反过来,你和你一个同乡用本国语言交谈时,把听不懂你们对话的美国人傻晾在一边是很不礼貌的.美国人可能会认为你们在议论他们或者说些不想让他们听到的话.如果你一定要换用本国语言来向一个非英语母语的同乡解释一些事情,至少你要为你的美国朋友翻译一下,让他们不要觉得自己被排除在外了.
更多地学习一些礼貌的英语表达方式,你就能自信地面对充斥着美国人的场所了.如果别人夸奖你的外表或者工作,礼貌的回应是“谢谢”(一个微笑或点头是不够的).回应“谢谢”的用语当然是“不客气”.如果有人问你 ”,别说你的患病经历.只要说“我很好,你呢?”最后,有人打喷嚏时你应该怎么说?虽然听起来不合理,但正确的回应是“愿上帝保佑你”,在美国就是这样.(据说西方人认为打喷嚏时灵魂有可能会溜走……)既然你学会了在美国的所有礼仪常识,你就能礼貌地运用英语了.我们希望你的美国朋友也会一样礼貌.
高一语文必修一重点字词
五中小qq1年前1
旧醅08 共回答了24个问题 | 采纳率91.7%
你去光华鼎力网站上看看,那里面有好多高考资料学习资料,赶紧看看吧,
德语mit用法一 Mit auf dem Gruppenfoto:eine schlanke Frau im knall
德语mit用法
一 Mit auf dem Gruppenfoto:eine schlanke Frau im knallroten Kostüm - die SPD-Abgeordnete Petra Merkel.
问mit auf dem gruppenfoto中mit怎么讲
二 Die Politikerin verteidigt kurz die Gesundheitsreform,die von ihrer Partei mit beschlossen wurde.
问 ihre partei mit中mit怎么讲?
三Ich finde auch diese Götter in Weiß gibt es eben lange nicht mehr.Und das muss man auch nach außen dokumentieren,...
问句中有两个动词,finden和geben,为什么?
四 Viele Senioren erregen sich über die neue Rentengarantie,die ein Sinken der Altersbezüge verhindern soll.Die einen loben die Schutzklausel,die anderen schütteln darüber den Kopf,
问die einen loben die 中die
嘻嘻
跑起来先1年前1
谁的猫猫 共回答了27个问题 | 采纳率88.9%
答 :
1.mit 在这里是副词,意思是 同样、还、也.
2.mit 在这里是动词的前缀,即mitbeschlossen(共同做出决定).
3.在Ich finde auch的后面漏掉了一个格点,即“ ,”(加上逗号后,此句便无语法错误).
4.Die einen 和 die anderen对应的是Viele Senioren .只是做名词化而已 .意思是“一些老年人”和“其他的老年人”.
高一必修一函数!
高一必修一函数!

877966911年前2
ptcboy 共回答了18个问题 | 采纳率88.9%
根据已知,得:√a+1/√a = 3
(1)
原式 = a+1/a = (√a+1/a)² -2 = 9-2 = 7
(2)
原式 = a² + 1/a² = (a+1/a)²-2 = 49 -2 =47
(3)
√a-1/√a = ±√(√a-1/√a)²} = ±√(a+1/a-2) = ±√(7-2) = ±√5
原式 = √a³ - 1/√a³ = (√a-1/√a)(a+1+1/a) = ±√5*(7+1)= ±8√5
一.单项选择.( )1.She_______big eyes and I_______small ones.A.has;
一.单项选择.
( )1.She_______big eyes and I_______small ones.
A.has;has B.have;have
C.has;have D.have;has
( )2.I________like a panda and you________like a panda,too
A.looks;looks B.look;look
C.looks;look D.look;looks
( )3.Li Ying has long_______and small________.
A.hair;ears B.hairs;ears
C.hairs;ear D.hair;ear
( )4._______are good friends.
A.Ben,Tom and I B.Tom,Iand Ben
C.I,Ben and Tom D.Ben,Iand Tom
( )5.Glad to meet you.
_______
A.Me,too B.The same
C.Hello D.I'm glad
( )6.Jim has a happy_______.
A.car B.house
C.eraser D.family
( )7.This is my friend_______name is jack.
A.He B.He's
C.His D.Him
宏尘1年前2
真的有网恋吗 共回答了14个问题 | 采纳率85.7%
C B A A B D C
一 When did your cousin begin to show his interest in medicin
一 When did your cousin begin to show his interest in medicine?
一 It was a Saturday _____ she noticed her uncle experimenting on a frog in his lab.
[ ]
A. that
B. what
C. when
D. which
qqqqai1年前1
关关和晃晃 共回答了8个问题 | 采纳率100%
C
数学成才之路必修一答案
皇骑宝宝1年前1
清潭w 共回答了15个问题 | 采纳率86.7%
答案是叫老师收了吧?可以去书店看看,
不过能自己做还是自己做的好
会做的直接就闪过去,找点突出性强的题做好了就行
老师布置作业主要是为了你们的学习
你让他知道你好好学了就没事了
作业不是目的!@
一立米等于多少立方厘米
largesea211年前5
皮卡老丘 共回答了17个问题 | 采纳率94.1%
1立方米=1000立方分米=1000000立方厘米
英语阅读理解一Passage One As I was leaving to meet Lynne,my roommat
英语阅读理解一
Passage One
As I was leaving to meet Lynne,my roommate told me that I’d better take some money,but I didn’t listen to him.I thought that Lynne would pay because she had invited me.
I arrived at the restaurant exactly on time.I’d been told that Americans expect you to be on time.Lynne and I sat at a table in the corner of the restaurant and a waitress came and took our order.
The dinner was a great success.I talked a lot about Saudi Arabia(沙特阿拉伯)and Lynne told me all about herself.After two hours the waitress finally came and asked if we wanted one check or two.Lynne said two.We went to the cashier(收银员)and Lynne paid her check.I was embarrassed(尴尬的)when the cashier gave me my bill.I had no money to pay for my meal.Then I had an idea.I pretended to look for something in my pockets and said,“Oh!I forgot my money!Can I call my roommate,please?” The cashier showed me where the phone was and I quickly called my roommate.
In a few minutes he arrived with some money,but he couldn’t hide how he felt.He laughed all the way home.
Now,I think it’s funny too,but at the time I was terribly embarrassed.I thought that an invitation to have dinner meant the same thing in the United States as in my country.I guess you have to understand that your customs are only your customs.When you visit a foreign country,you have to learn about their customs,too.
Choose the best answer according to the passage (根据短文内容,选择最恰当的答案):
( )1.The writer’s roommate advised the writer to take some money with him .
A.to pay for the meal B.to share the cost of the meal
C.to invite Lynne to dinner D.to pay the checks
( )2.The roommate laughed all the way home because .
A.the writer was embarrassed when he couldn’t pay his check
B.the writer telephoned him to bring some money to him
C.the writer hadn’t told Lynne the truth
D.the writer would not listen to him when he left the house
( )3.The writer and Lynne .
A.enjoyed their meal very much B.successfully finished their meal
C.had a talk for two hours D.traveled to Saudi Arabia together
( )4.Customs can be in different countries according to this passage.
A.quite the same B.entirely different
C.close to each other D.very similar
( )5.Why didn’t Lynne pay the check for the writer?
A.Because she didn’t have enough money with her.
B.Because she didn’t want to do so.
C.Because she thought it was natural for people to pay their own check.
D.Because she wanted to embarrass the writer.
水口水西1年前1
温香软玉抱满怀 共回答了10个问题 | 采纳率100%
B D A B C