请简单明了,答题时请表明题号 第一题：36比_______少五分之一第二题：一段路,甲用10小时走完,乙用8小时走完,两

i watched a red and blue pulsating object move like a hummingbird for about 1/2 an hour.2 more similar objects went into the direction of the object.all of them disappeared behind the trees after 1/2 an hour or so.but i was watching mostly just the one pulsating one for at least 1/2 an hour.it seemed to be hovering,but then also moving like a hummingbird at times.sometimes it moved in a figure eight pattern and sometimes in a circular pattern.i definitely have never seen anything like it before.it was NOT a satellite,plane,helicopter,star,comet,or weather balloon.the sky was completely clear with no clouds and there was no wind.i watched it outside on my deck.it made me feel,of course,incredibly excited,anxious,awestruck

张力在物理里的意思是扩展.
用到文学或艺术上指的就是知识面比较广.
比如说张国立塑造了各种各样的角色,就可以认为他有着很强的艺术张力.
不过这个词现在都用烂了.

要解这个问题
首先要明确基础解系的定义
基础解系的定义是AX=O的解空间里的一组基
所以那个ζ1~ζn-r是线性无关的
你那个解法是可以的

以下都是我的经验,化学方程式首先要找到那些是反应物,那些是生成物,然后就是根据质量守恒配平,对于离子式还有电荷守恒,对化学方程式,根据几个守恒就可以了,在平时的学习的时候要找到规律,什么跟什么反应生成什么,特别注意对于有机和无机化学方程式的不同进行比较和鉴别!

使用787mm*960mm这种尺寸的纸对折4次进行裁剪而成的纸张尺寸大小.(裁剪出的纸张只有原来纸张的1/16大小)

fade out :淡出,消失

可造句：The singer gradually fade out of the public.
可译为：这个歌手渐渐淡出了公众的视线.

知识点：1.第一个the表示特指,特指某位歌手.
2.第二个the+名词或形容词表示 ”一类人”,
比如 the public,表示公众；the rich ,表示富人

一、为什么水可以灭火
水可以灭火主要是物理上的原因.着火的三个条件：温度、可燃物、助燃剂
水灭火是降低温度,因为水不可燃而且比热很大（几乎是最大的了）
ps,干粉灭火器是隔绝助燃剂
二、为什么铁会生锈
铁常温下化学性质活泼（容易失去电子,电子容易被别的分子获取）,而且常见的铁都含有一定杂质,更容易跟别的物质起化学反应,常见的特别是跟潮湿空气中的氧,反应生成三氧化二铁,这就是铁锈的主要成分.铁锈很疏松,很容易吸水,更加剧了生锈的反应并且容易脱落
三、为什么电池可反复使用
不是所有的电池都可以反复使用,只有充电电池可以.
电池充电的时候,有电子通过,电池中的被耗尽能量的电解质得到了电子,重新产生反应,蕴藏了能量,放电的时候,这个能量释放出来产生了电荷,而电解质也产生了另外的反应,不再是电解质了,所以电池就没电了.

一Have you ever taken a picture with Santa Claus?Last Sunday.I went shopping with my friend Lucy.The shopping mall was really crowded.There were many kinds of Christmas gifts.We were so exited.Just th...

轮系中的首轮转速 ：轮系中的末轮齿数

观察,有沉淀的为浊液,用集中光束照射,能通过的,即在杯子的另一边可看到一个点的为胶体,分散的为溶液,

1定义,对所有的x,都有f(x+T)=f(x),这种方法一般
2三角函数y=Asin(ax+b)周期为2pi/a
3对于一般函数f(x+a)=-f(x),则周期为2a;f(x+a)=1/f(x),周期为2a等
4通过图像,看图像的重复

1.配平化学方程式的原理
　配平化学方程式就是在化学式前面配上适当的计量数,使式子左、右两边的每一种元素的
原子数目相等,体现质量守恒定律．
2.配平化学方程式的方法
①.最小公倍数法(以磷在空气中燃烧反应为例)
P + O2 = P2O5 → 4 P + O2 = 2 P2O5
②奇数配偶法(以氯酸钾分解反应为例)
MnO2 MnO2 MnO2
KClO3 ------- KCl + O2↑ → 2 KClO3 ------ KCl + 3 O2↑ → 2KClO3 ------- 2KCl + 3 O2↑
△ △ △

1、用待定系数法 2、已知x求y或已知y求x 3、由图像法解 4、题目中有顶点的,一般用y=a(x+h)2+k 5、有交点的,一般用y=a(x-m)(x-n)

1 酸拓羟基醇脱氢.基本公式.把分子式写大一些把羧基和醇羟基拉在一条直线上.R—O H+HO-C-R
//
O 记得加水 +H2O
2 同分异构要从碳链异构开始然后官能团异构.最后利用不饱和度数氢的个数.记住书写之中的对称和翻转 注意技巧如：苯环的二氯与四氯取代是一样的 丙基的同分异构有两种所以丁烷的同分异构有两种.丁基与戊烷.丁基与一氯丁烷.（1）环氧氯丙烷 一个环一个不饱和度 又没有双键但有一个氧一定有酮基（羧基）不知道你们环丙基算不算所以答案不好说（2）蒽十个不饱和度三个苯环上的异构有23种 三个位置.注意对称.
3 通过不饱和度记忆一个环一个不饱和度；一个双键（碳碳、碳氧）一个不饱和度、氧单键不占不饱和度【这种氧只要在最后加上就行了】.
4 氧化还原如果记不住公式 也可以按无机的配 写成分子式氢+1氧-2碳就看着办吧.
希望对你有帮助.

你好!这是一个关于三角函数的问题 还可以假定一个圆心出来,在连接另外两点 可以做出一个三角形 ,做一条垂线 应为圆心角知道为A 两点的距离也知道为a 设半径是r 则可以列出 sin A/2 =a/r 就可以算出半径 之后就可以画图了
采纳哦

空集
定义：不含任何元素的集合成为空集.
表示方法：用符号Φ表示
性质：空集是一切集合的子集.
举例：{x~2+1=-2}=Φ

将目的基因导入一块基因芯片上,由于基因互补配对原则,会是目的基因与提供的已知基因的同源片段对应组合.结合在已知基因上的标记分子就会被计算机检测出来,从而判断目的基因上有对应的片段

有些固定搭配 to是介词 后面必须加ing 比如：admit to承认,confess to承认,
be accustomed to 习惯于,be used to 习惯于,stick to 坚持,turn to开始,着手于,devote oneself to 献身于,be devoted to 致力于,look forward to 盼望,pay attention to 注意 prefer…to…、 become accustomed to、object to、be addicted to 、be opposed to、 be given to 、be reduced to 、be attached to、be adjusted to 等等.

楼上的正解,呵呵
我说个严肃点的：假如我站在这不动,楼主以100米每秒的速度往南奔,对我来说你就是以100米每秒的速度往南移动；如果我以150米每秒的速度往南跑,楼主以还是以100米每秒的速度往南跑,那对我来说你就是以50米每秒的速度往北移动了!
所以任何事物都是相对的!同样一件事情,从不同的角度看可以得出不一样的结果哦

主要原因二氧化碳等温室气体的大量排放.
人类生活的影响：全球变暖,气候带发生混乱转移.海平面上升,沿海城市被淹没.

请看下列例题：
硫酸氢钠和氢氧化钡反应有两种反应方程式：
1.NaHSO4+Ba(OH)2=BaSO4+NaOH+H2O
2.2NaHSO4+Ba(OH)2=BaSO4+Na2SO4+2H2O
对于1反应来说是氢氧化钡过量
对于2反应来说是硫酸氢钠过量
我们判断的方法可以用过量的该物质放入生成物中,看是否还会继续反应,如能反应说明该物质没有过量；如不反应就是该物质已经过量.
离子的情况：将反应方程式改写为离子反应方程式,同上理分析判断即可.

规律不是很明显,主要是记忆.
长单词很多重音在倒数第三个音节上.
例如'beau/ti/ful;per/se/'ver/en/ce.

响度 声音的强弱 音调 声音频率的高低 音色 声音的感觉特性
希望采纳

1、这种“父子协议”很有创新意义.断了我们衣来伸手饭来张口的后路,促使我们独立面对现实生活.
2、暂时可能接受不了,慢慢地能体会父亲用心良苦.
3、 传统道德,是指一个民族由历史沿袭而来的道德观念伦理思想的综合体.它具体体现在人们的行为方式、风俗习惯、心理特征和价值观念上,内化积淀于每个社会成员的心灵深处,是民族精神的重要内容,也是民族传统文化的主要载体.一个民族传统文化之所以得到传承和延续,是这个社会成员的社会道德观念自觉认同的结果,而决不是以强制性得以延续和发展的,因此,只有正确地对待传统道德文化,才能正确地对待整个民族的传统文化.而传统文化固具有极大的相对稳定性,它往往是反映和代表了一个民族的社会整体意识和行为倾向,并使得传统文化得以传播和积累.因而,传统文化要想对现代文化具有正确地导向性,就必须坚持现代化与民族化的统一,又可以坚持反对过了时的所谓的保守的复古的意识现象的发生.

比热容越大,升高到同样的温度需要吸收的热量越多,反之比热容越大降低同样的温度释放的热量越多.

诗人陆游以一个“游”字贯穿全诗的主线,生动地描绘了丰收之年农村欢悦一片的气象和乡间的风光习俗,刻画了农民淳朴、好客的品性,表现了诗人对农村生活的真挚感情.第一、二行诗写不要笑话农人田家的腊酒浑浊不清,丰收年景款待客人,菜肴尽够丰盛.一个“足”字,表达了农家款待客人时尽其所有的盛情.第三、四行诗写山峦重重,水道弯弯,正疑无路可走,突然出现柳阴深深,鲜花簇簇的景象,而眼前又是一个山村.“山穷水复疑无路,柳暗花明又一村”,善状难写之景,又于写景中寓有一定的哲理,成为千古传唱的名句.现在常用以形容陷入困境,似已无望,忽而绝处逢生,出现新的契机,增强克服困难的信心.主要写了诗人做客山村,表达了诗人对乡村生活的热爱之情（田园生活的热爱之情）

Going to morning market has been many people's habit in Beijing.

解
密度函数的积分就是分布函数

奇数位各个数字相加－偶数位各个数字相加是7或11的倍数.

My hometown is located in a very beautiful place. It was once a green city. But now it is becoming dirtier and dirtier. Lots of buses are running on the streets and plenty of factories are built around my hometown so that the heavy smoke is the most usual view there. Besides, more and more trees are cut down, as a result, we can not hear the birds singing in the blue sky. But I still love my hometown like before. It is in the place that I was born. So I hope that we can take action to change our hometown into that beautiful place like before.

⑥固：固然、诚然.槁：干枯. ⑦心：思想,精神.固：岂,难道. 死灰：已冷却的灰烬.原指心境淡漠,毫无情感.现也形容意志消沉,态度冷漠到极点.
外形（或形体）固然可以让一个人像干枯的树木,思想、精神也可以让一个人像已经冷却的灰烬吗?

（形体诚然可以使它像干枯的树木,精神和思想难道也可以使它像已经冷却的灰烬那样吗?）

of
1....的,属于
One of the legs of the table is broken.
桌子的一条腿坏了.
Mr.Brown is a friend of mine.
布朗先生是我的朋友.
2.用...做成的;由...制成
The house is of stone.
这房子是石建的.
3.含有...的;装有...的
4....之中的;...的成员
Of all the students in this class,Tom is the best.
在这个班级中,汤姆是最优秀的.
5.(表示同位)
He came to New York at the age of ten.
他在十岁时来到纽约.
6.(表示宾格关系)
He gave a lecture on the use of solar energy.
他就太阳能的利用作了一场讲演.
7.(表示主格关系)
We waited for the arrival of the next bus.
我们等待下一班汽车的到来.
I have the complete works of Shakespeare.
我有莎士比亚全集.
8.来自...的;出自
He was a graduate of the University of Hawaii.
他是夏威夷大学的毕业生.
9.因为
Her son died of hepatitis.
她儿子因患肝炎而死.
10.在...方面
My aunt is hard of hearing.
我姑妈耳朵有点聋.
11.【美】(时间)在...之前
12.(表示具有某种性质)
It is a matter of importance.
这是一件重要的事.
for
1.为,为了
They fought for national independence.
他们为民族独立而战.
This letter is for you.
这是你的信.
2.代替;代表
We used boxes for chairs.
我们用箱子当椅子坐.
3.因为,由于
I am sorry for what I said to you.
我后悔不该对你讲那些话.
4.在(指定时间)
The meeting is arranged for 9 o'clock.
会议安排在九点钟.
5.(表示时间、距离等)达,计
You can see for miles from the roof.
你站在屋顶上可以看到数英里之外.
6.对于,关于;在...方面
I am too old for the job.
我年纪太大,做不了这工作.
7.为得到,为赢得
He sent the waiter for a packet of cigarettes.
他让侍者去拿一盒香烟.
8.以...为代价;以...交换
He sold his car for 500 dollars.
他以五百元把车卖了.
9.当作,作为
Do you take me for a millionaire?
你是不是把我当百万富翁?
10.赞成;支持;倾向于
Are you for the government or against it?
你是支持还是反对政府?
11.朝...方向去;往,向
He left for Taipei.
他出发去台北.
12.就...而言
She is sophisticated for her age.
就年龄而言她是世故了一点.
conj.
1.因为,由于
We must start early,for it will take two hours to drive to the airport.
我们得早点动身,因为开车去机场得花两个小时.

动量公式.爱恩斯坦相对论.粒子加速器.

10绡囨垜甯?湅鍙嬪啓鐨 6.October 24th Monday Sunny My pencil case Class 4,Grade 6 Yao Yuhong I have a nice pencil case.It is orange and black.There is a ruler,an eraser and some pencils in it.They are good friends.They often help each other.When the pencil writes wrong words,the eraser often helps it rubber them away.When the pencil wants to draw a straight line,the ruler often helps it draw the straight line.If I want to have a good score,I can鈥檛 without them.7.November 8th Tuesday Sunny Chalk Class 1,Grade 6 Li Jiacheng As a student,we see chalk everywhere.Some chalk is white,some is colourful.It is about 6 centimeters long.It is often used by our teachers.It is the 鈥減en鈥 for our teachers.It becomes smaller and smaller,while we grow taller and taller.We never think it鈥檚 important.Sometimes we use chalk to play with or to throw at one another.One day when I saw the teachers鈥 hands,they are all full of chalk dust.From then,I have a different feeling about.I love chalk because I love my teachers.8.November 21st Monday Sunny My toy bear Class 3,Grade 4 Hu Yuelu I have one toy.It鈥檚 a bear.This toy bear looks so lovely.This toy bear is my birthday present from my dear uncle.This toy bear is brown.It has two small eyes and a small nose.The toy bear is in a black hat and a bright scarf.Look at his jacket,it鈥檚 blue.His trousers are beautiful.They are red.I put it on my bed.When I sleep,I always put it in my hug.I can鈥檛 sleep without my toy bear.I like this toy bear.I hope you like this toy bear,too.9.A page from a student鈥 diary July 14,2002 Sunday sunny Today I began to learn 鈥淟i Yang鈥 English.At first I was very afraid because my English is not very well.But after ten minutes,I was not afraid it,the lesson is not as hard as I think.Instead,it is so easy that I can remember twenty sentences in fifteen minutes.After it .My mother ask me some English questions,I can answer it quickly except two of them.Now I am writing my first 鈥淓nglish dairy鈥?I hope I can write it everyday.Why not write it with me,classmates?10.A page from a student 鈥檇iary (two) July 15,2002 Monday sunny Today I have to do much housework.First wash the clothes ,then cook the meal銆乼idy the room.In the afternoon,I met a friend named dengyuming.We played computer game all the afternoon.When all the things have been finished,I only want to go to sleep because it is ten now.But when I began to sleep,I remembered that the computer wasn鈥檛 close.So I could only stand up and close it.Then I was fall asleep.Now,I hope everything goes well!11.A page from a student鈥檚 dairy (three) 鈥淲hy we must study all the day?We can only have free time when we have lunch and super.Sometimes I nearly have no time to go to sleep.In our life,there is only work.Nothing else.鈥 Today I read the passage,I can only say:鈥渢hat鈥檚 too bad鈥?Is it?I think we should work for everybody,not ourselves.If we work for ourselves,we cannot work for long and good.For example:maozedong,zhouenlai and so on.I wish we could work as them.12.A page from a student鈥 dairy (four) The life of man likes the theatre When I was born,I usually stop at nothing like a hare.Nine years later,I am very happy in my study.Everyone likes me.Now,I am crying when I write this passage.Not anything else,only for my fail in the middle exam.What will me like later?The life of man likes the theatre,everyone in the theatre.In the theatre,it would not have presents,but it would have friends.No friend is the worst of our life.13.A page from a student鈥檚 dairy (five) July 18,2002 Tuesday windy I didn鈥檛 finish my work today.I didn鈥檛 write the English dairy.My mother was very angry because she has keen me to get ahead in the career.I know that she is good for me,but I don鈥檛 know how to say now.May be I lacks confidence in myself.Now I am writing my English now.From now on I will force myself to practice English and do exercise.I hope I can be turn better tomorrow.Today I knew a new word:practices makes perfect.14.A page from a student鈥檚 dairy (five) July 18,2002 Tuesday windy I didn鈥檛 finish my work today.I didn鈥檛 write the English dairy.My mother was very angry because she has keen me to get ahead in the career.I know that she is good for me,but I don鈥檛 know how to say now.May be I lacks confidence in myself.Now I am writing my English now.From now on I will force myself to practice English and do exercise.I hope I can be turn better tomorrow.Today I knew a new word:practices makes perfect.15.A page from a student鈥檚 dairy (six) Today I came back from a place named 鈥渉e chuan鈥?it鈥檚 a good place.There has some nice view like chang jiang river.I came there in two days ago.Our aunt is here.We had a good time in there.But I also write English dairy too.Because of the wrong computer,the message didn鈥檛 here.I wish myself to live more better tomorrow.

1
你自己在整理整理吧,加油!
1.
Summer Vacation
I enjoy summer vacation very much.Because summer vacation is the longest vacation of the year.We have more than fifty days to rest.Though it is very hot,we can either go to swim or stay in the air-conditioned room .In the evening,I like to go shopping with my friends.We can eat many things in summer,such as ice creams,watermelons,grapes,and so on.In summer,I always go on a trip with my parents.It's a good chance for us to visit some nice interesting places.
2.
I often go to see my grandma and grandpa during my summer vacation.They are both seventy years old and live in the country happily.Summer view of the countryside is very beautiful.I can do many interesting things there.I am used to getting up early in the morning,breathing the fresh air,listening to the birds singing,and enjoying the green trees,red flowers and the river.I like fishing with my friends.When night comes,I sit under the tree with my grandma,listening to her telling me many funny stories.And I tell her some new things happening in the city.When I have to go back,I am always reluctant to go.I really feel happy living in the country.
3.
A new term began.Students all returned to school and met again.They were talking about what they had done in the holidays.I was much happier.I couldn't wait to tell my story.Now it's my turn.I told them I got a job in a restaurant.I worked as a waitress.They didn't believe at first.
"Yes,it's true."I said," I really had a hard time at the beginning.But several days later,I could do a good job.I earned six hundred yuan this holiday."They all looked at me with their mouths open.

有个姓秦的士人好古物成瘾,即使价格再高他也要千方百计地买回家来.有人也就投其
所好,专门钻他这个空子,让他吃亏不少.
一天,一个人扯着一块烂席片来见他,说是以前鲁哀公向孔子问政时赐孔子的座席.秦
士心中大喜,认为这是难得的古物,就以诸多良田作价买了下来.
过了些时候,又有一个人手持一把古杖找上门来,说：“这是以前太王为避夷狄之乱杖
策离开豳地时所持的杖棰,比孔子所坐的席子还要早几百年呢!如此古物,您该出什么价
”秦士就倾尽家中资财买了下来.
没过多久,又有一个人手捧一只朽烂的木碗来兜售,对秦士说：“您买的席和杖,都算
不上古物.我的这只木碗是夏桀所造,比周朝古远多啦.”秦士没想到竟能遇到如此古物,
就把正住着的宅院作价买下了这只木碗.
秦士三件古物到手,却落得田资用尽,无衣无食,然而好古之心却使他始终不忍丢弃古
物.于是,秦士就披上“哀公之席”,拿着“太王之杖”,捧着“夏桀之碗”,沿街乞讨,
糊口度日,口中还不时地喊着：
“衣食父母们啊,您若有太公时的九府钱,就行行好,给我一文吧.”
我只能帮到这,可能有点错,原谅啊

物质的量是高中的
化学：
【1】.先认识元素,背好前20个元素
氢氦锂铍硼 碳氮氧氟氖 钠镁铝硅磷 硫氯氩钾钙
【2】.然后是认识物质分类
物质分纯净物和混合物,纯净物分单质和化合物,化合物分酸、碱、盐和氧化物
【3】.性质
O2（氧气）具有多性质：1.可供进呼吸 2.炼铁等
【4】燃烧3个条件：1.要有可燃物2.要有助燃物（空气或氧气,最好说空气,因为后来会学到只有镁和氮气就可以燃烧,说明燃烧不一定需要氧气）3.要达到可燃物的着火点（注意：有些题目说降低着火点都是错误的,着火点不可降低,是物质的一种基本性质）
【5】化合价：每个原子的质子数和核外电子数相等,达到稳定状态时最外层电子数为8（氢和氦最外层电子数为2）,此时电子带负电,质子带正电,电子数的负电与质子数的正电相加就是该元素在化合物中的化合价
【6】化合物中总化合价为0
比如CO2（二氧化碳）C+4价 O-2价 （+4）+（-2）*2＝0
【7】质量守恒定律：化学方程式要用到,等号两边的总相对质量一定相等,还要记住元素的相对原子质量（一个元素相对于一个碳12原子的质量）
【8】化学方程式：前提是学会写元素符号,然后学会写化学式,最后学会写化学方程式,配平是为了保证等号两边相同元素的原子数相同

比如说一个人,如果你要看他长得好不好看,很明显不能把看成一个点；而如果你要看他从南京跑到北京用了多长时间,就不用管这个人胖和瘦,高和矮,看成一个点就行了
就是说把这个有质量的东西看成一个点,不能影响你的研究

提这个问题,应该楼主没有弄清楚主、谓、宾这些句子成分的定义.
主：动作的发出者
谓语：就是动作
宾语：就是动作的承受着
举个例子：He hit me.他打了我.在这个简单的句子中,楼主要是清除“动作是什么（hit打）、谁发出了动作（he）,谁接受了动作（me）”不就明白什么是主谓、什么事主谓宾了吗?
其次,楼主在重温一下谓语的定义——谓语是对主语动作或状态的陈述或说明,指出“做什么”、“是什么”或“怎么样”.
然后,清楚谓语的分类——就是一些及物动词、不及误动词和系动词.这里,楼主说的“主系表”就是这个“系动词”了.
如：She is very beautiful.这里的is就是一个系动词,beautiful漂亮的就是表语.
分析句子成分其实很简单,就两步：
1、找句子主干,即主谓宾（找出主谓宾之后,整个句子你就可以明白个大概了）；2、分析句子的修饰部分——修饰主语、修饰宾语或修饰整个句子的枝叶部分（弄清楚句子的枝叶部分后,你就会明白整个句子了）.
其实,我觉得学习分析句子类型和成分根本不用背,方法就是多去试着分析句子,掌握其规律以后就好办了.毕竟,实践永远是最好的老师!
我也很喜欢英语,所以我回答很认真的.楼主还有问题的话,欢迎追问

例如,溶液甲是物质A的水溶液,现在我们要测定甲中A的浓度,我们可以用以知物B的溶液乙来滴定（其中B的浓度以知）.我们之所以用B的溶液做滴定液是因为乙溶液加如甲溶液后会有明显的现象.比如滴定NaOH溶液时我们可以用以知浓度的盐酸,把盐酸缓慢滴入混有酚酞的NaOH溶液中,当溶液颜色由红色恰好变为无色时（恰好指的是在最后一滴盐酸滴入前溶液还呈粉红色）并且半分钟内不变色,这就是滴定的终点,我们根据消耗掉盐酸的量可以计算出NaOH的浓度.
沉淀溶解的原理是一样的,只不过利用了反应时生成沉淀这也现象来指示滴定的终点.当不再有沉淀生成时就为滴定终点喽~

设该直角三角形的已知角为∠A,已知直角边为∠A的对边a,直角为C,斜边为c.
由三角正弦函数的定义得：
sinA=a/c
则,c=a/sinA.
若已知直角边为∠A的邻边b,即该边与斜边的夹角为∠A.
同理,由余弦函数的定义得：
cos∠A=b/c.
则,c=b/cos∠A.
若已知锐角为∠B,可仿此做法就是.
给出的就是公式!

上面得答案已经非常精彩,我补充一点：注意到BD=PB
加上BM垂直PD
所以M显然是PD中点.
然后一切都出来了.

1.配方法(最垃圾的方法,不推荐)
2.因是分解(最快,但是最难的)
比如,X^2+2X+1=0
(X+1)^2=0
X+1=0
X=-1
3.公式法.就是求跟公式
方程AX^2+BX+C的两个根为X1=[-B+根号(B^2-4C)]/2A
X2=-B-根号(B^2-4AC)/2A
其中,B^2-4AC称为根得判别式.用来判定根的个数的.

这个,如果用在小地方用at,大地方用in.不过不长篇大论这两个词很难讲清楚,因为他本来涉及的领域就很大.除非你把具体的题目放在这里分析.

日 由 田 中 十 一 口 曰 甲 干 士

显性性状由显性基因控制,只要出现这种基因就显该性状.如A控制显性性状,那么AA、Aa就显显性性状.
隐形性状由隐性基因控制,要全都是隐性基因才显该性状.如a控制隐性性状,那么只有aa才隐性性状.

D 酸性：单炔＞单烯＞烷烃.
我是从杂化轨道去理解的.
吸电子能力SP>SP2>SP3,相应的对质子（H）的吸引能力相反,即SP

∵∠A是三角形中的一个角,不等于0∴0＜tanA

主语表示句子主要说明的人或事物,一般由名词.代词.数词.动名词.动词不定式等充当
谓语说明主语的动作,状态或特征.行为.
宾语表示动作行为的对象,跟在及物动词之后,能作宾语的有名词,代词,动名词,数词,动词不定式等.
例如：I eat an apple.
I为动作的发出者,主要说明的对象,为主语
eat为I的动作,是谓语
apple是跟在及物动词eat后,我吃的对象,为宾语
宾语从句：在句子中起宾语作用的从句叫做宾语从句
如I wonder who she is,
我想知道她是谁
I为主语,wonder为宾语,who she is跟在wonder后面做宾语结构,即为宾语从句