学考模拟题（数学）如图,已知在侧棱垂直于底面的三棱柱ABC-A1B1C1中,AC=3,AB=5,BC=4,AA1=4,点

though。。。。。。。。where
一空一词的答案

C
生物进化的途径是自然选择,即拥有不同变异个体的群体接受环境的“优胜劣汰”式的选择,最终产生具新性状的物种.
A毋庸置疑是对的,因为它直接说是自然选择的结果,这无可辩驳.
B狼是鹿生存的一个环境因素,鹿野是狼的生存环境因素.作为各自的生存环境因素,当然在相互选择、共同进化者.
C这是拉马克的用进废退理论,现已被证实其错误.磨练出来的尖牙是不能遗传下去的,所以它在进化上没有多大意义.
D猫头鹰和老鼠同样是相互选择的.这里说到了老鼠对猫头鹰的选择.

楼主先别着急,我觉得过六级还是有戏的.还有1个月,再加紧练习是没有问题的.还有我想告诉楼主,听力,一般市面上卖的听力都比实际要慢一些.我是去年12月考,可能那次题比较变态,听力考惨了,我掐了一下时间.35分钟的听力只放了30分钟.

推进你做剑桥2,3,4,5,6和雅思阅读真经1,2这上面的都几乎都是以前考过的题有必要做一下.雅思阅读练完后没有必要把每篇文章当精读课文来学,那么多学的完吗?所以大部分文章只需记里面的词汇.

理解没出问题,完全正确.这题出的叫别扭,只能说相较于ABC那些不靠谱的,D相对靠谱.
比如说,准确来说,马王堆是在长沙附近郊区的一个坑里发掘的,但是大家照样也说在长沙发掘的马王堆,对不?
如果考试真遇到这么不靠谱的题,硬选用排除法还是选的出来的,别担心.

应该是A吧,B选项的“昼夜温差大,冻融作用强”没有错,但是阴坡的昼夜温差应该小吧
C,北坡的确是冬季风迎风坡,但是干燥的西北风不会带来降水
D,夏季风是带来降水的（其实一看这地方是在东北,CD都可以不用考虑了）

大家都说明了正确被动语态是前面那个.
真要问后面为何不对的话,只能这么解释：被动语态的句式中不能出现助动词 do,基本上是只能以 be + 过去分词来表述.所以后面问句中的 did 就已经是很好的线索了.

向量EF=k·向量BE=k·（-向量AB+1/2向量BC）=-k·向量AB+k/2·向量AD
m/n=-2望楼主采纳,楼主辛苦了

PB⊥底面ABCD,CD⊥PD,可以得出CD⊥BD,
底面ABCD为直角梯形,AD‖BC,AB⊥BC,AB=AD,很容易得出△CDB和△BAD都是直角三角形,故得：BC=6,
点E在棱PA上,且PE=2EA.可知E在三等分点上,
我们以B为原点,以BC、AB、PB分别为X轴、Y轴、Z轴,则
A( 0,3,0 ),B( 0,0,0 ),C（6,0,0）,D( 3,3,0 ),P(0,0,3 )
易得E(0,2,1) ,（其z轴是P的1/3,y轴是BA的2/3）,
（Ⅰ）过A做AF‖CD交BC于F,故异面直线PA与CD所成的角就是∠PAF,
不难证明AF=PF=PA=3√2,PAF是等边三角形,
故∠PAF=60°,
异面直线PA与CD所成的角是60°.
（Ⅱ）直线PC方程为x+2z=6,y=0,
设平面EBD方程为ax+by+cz+d=0,
代入B、D、E坐标可得d=0,a=b,c=2b,则有
bx+by+2bz=0,即x+y+2z=0,
当y固定时,即一条关于xoz平面的斜率与直线PC斜率相同的直线,
故PC‖平面EBD；
【也可以把直线PC方程代入平面方程,看是否有解,有解则相交,无解则平行,将x+2z=6代入得y= -6,而直线为y=0,显然无解,】
（Ⅲ）BE方程为y=2z,x=0,
因为DA⊥yoz平面,设BE所在直线上一点G（0,2z,z）,
则∠DAG的正切值是DA／AG=3²／√[（0-0）²+（2z-3）²+（z-0)²]=9／√（5z²-12z+9）,
当tg∠DAG值最大时的角就是二面角,
DA是固定的,当AG最小时（此时AG⊥BE）即分子最小时值最大,得tg∠DAGmax=3√5,
故二面角A—BE—D的大小为arctg3√5.

就5分?

C.拨号网络

初一英语试卷
一.选择填空.
( )1. What do you have ____________ supper?
A. for B. at C. with D. on
( )2. She isn' t good ___________ maths. Could you help her __________ her maths?
A. with, with B. at, at C. with, at D. at, with
( )3. We should learn ____________ each other.
A. to B. with C. from D. for '
( )4. Are you ____________ music?
A. listen to B. listening to C. listening D. listen at
( )5. When ____________ Mary ____________ to school?
A. is, go B. do, go C. do, goes D. does, go
( )6.What do you often do ____________ Sunday morning?
A. on B. in C. at D. for
( )7. There ____________ a lot of food at home.
A. are B. is C. have D. has
( )8. Do you have ____________ to buy a computer?
A. many money B. enough money C. money enough D. a lot money
( )9. What about ____________ computer games.
A. to play B. to playing C. playing D. play
( )10.Excuse me, we can't ____________ our tickets.
A. look for B. find C. to look for D. to find
( )11. ___________________ are Young Pioneers.
A. All student B. All of students C. All of the students D. All students
( )12. The birds are singing ____________ the tree.
A. on B. in C. of D. at
( )13. We are doing ____________.
A. our homeworks B. us homework C. we homework D. our homework
( )14. Some girls are on the hill. Where are ____________?
A. another girl B. others girls C. the other girls D. the other girl
( )15. What are they doing? They ____________.
A. take photos B. are taking photo C. take a photo D. are taking photos
( )16.How do you_____this book?
A.read B.want C.like D.write
( )17.Who teaches_____English this team?
A.we B.us C.our D.ours
( )18.She doesn’t like milk but likes orange______.
A.at all B.little C.a lot D.a lot of
( )19.There are _____pens_____pencils in the box.
A.not ,and B.no,and C.don’t,/ D.no,or
( )20.He is_____American.I’m_____E nglish.
A.a,a B.an,a C.the,the D./,/
二.完形填空
I am a middle-school student. Now let ___1___ tell you something ___2___ our classroom.
It's very ___3___. There are two maps ___4___ the back wall. ___5___ is a map of China.
___6___ is a map of the world (世界).
There are ___7___ desks and chairs in our classroom. There is a big desk ___8___ the
teacher in the front of it. We ___9___ four classes in the ___10___ and two in the afternoon
1. a. I b. my c. me d. we
2. a. about b. in c. on d. at
3. a. small b. big c. bigger d. biggest
4. a. in b. on c. under d. over
5. a. It b. It's c. One d. one
6. a. Other b. Others c. Another d. The other
7. a. fourty b. forty c. forteen d. fourteenth
8. a. for b. of c. to d. about
9. a. there is b. there are c. has d. have
10. a. moning b. mourning c. morning d. moring

三.阅读理解.
A
Jan：I have new photos of my family, but they' re not very good. This is my sister…
Mark：Where is she? Is she at the library?
Jan：No, she' s in the living room. She s doing her homework. And that s my brother.
Mark：Is he doing his homework, too? What's he eating?
Jan：He' s watching a scary movie on TV and eating french fries.
This is a picture of my aunt and my mother.
Mark：Is that -your mother in the pool?
Jan：No, that's my aunt. My mother can't swim. And this is my mother and my aunt at the shop. They really like shopping and eating at the shop. Mark: Interesting photos.
( )1. The pictures are ______.
A. good B. interesting C. scary
( )2. Jan' s sister is doing her homework ______.
A. at the library B. at the pool C. in the living room
( )3. Jan' s brother isn' t ______.
A. doing his homework B. watching TV C. eating french fries
( )4. Jan' s ______ can' t swim.
A. sister B. mother C. aunt
( )5. Jan' s mother and aunt like ______ at the shop.
A. eating french fries B. shopping C. swimming
B
阅读短文,判断正误.正确的写“T”,错误的写“F”.
Mr Jones and Mr Brown work in the same office (办公室).One day Mr Jones says to Mr Brown ,

“I will have a small party at our house on Monday evening . Would you and your wife like to

come ?”

Mr Brown says , “Thank you very much . I’d love to , but let me ask my wife first .”

So Mr Brown goes to the other room and telephones his wife . Then he comes back and looks very

worried .

“What’s the matter?” asks Mr Jones . “Is you wife there at home ?”

“No,” answers Mr Brown . “She isn’t there . My small son answers the telephone . I

say to him , ‘Is your mother there , David ?’ and he answers ‘No , she isn’t in the

house.’‘Where is she ?’ I ask ,‘She is somewhere outside(在外面) .’‘What’s she doing?’

‘She is looking for me .’”

1．There is a party at Mr Jones’s house on Monday evening . ( )

2．Mr Jones asks Mr Brown and his wife to go to the party . ( )

3．The telephone is in Mr Brown’s office. ( )

4．Mr Brown speaks to Mrs Brown on the telephone . ( )

5．Mrs Brown is looking for her son . ( )

C
One Sunday morning Mr Green and his child , Bill ,are in a big shop . Mr Green wants to

buy a new blouse for Mrs Green . Bill likes oranges , so his father buys two kilos(公斤)of

oranges for him , too . Bill wants to buy some picture—books and colour pencils , too . There

are many people in the shop . They are men and women , old and young . They all want to buy

something there .

6．Mr Green goes to the shop with ___.

A．Mrs green B．his son C．his daughter D．his father

7．Mr Green wants to buy a new blouse for ___.

A．Bill’s mother B．Bill C．his friend D．other people

8．Bill likes ___.

A．all the things B．the new blouse C．oranges D．orange

9．Bill wants to buy ___.

A．some picture—books B．some colour pencils C．clothes in the shop D．A and B

10．The shop is ___.

A．empty B．close C．full of children D．full of people

四.短文填空
On weekdays, Mary _1_ (get) up at 6:30. She _2_ (have) breakfast at home and then she _3_ (go ) to school. She _4_ (get ) to school at about 7:30 every morning. She _5_ (not like) to be late.Mary _6_ (have) four classes in the morning and at two in the afternoon. Classes are over at 3:40. Someimes she _7_ (play) games with her classmate（同学）. Sometime she _8_ (fly) kites. She _9_ (get) home at 4:40.
In the evening she often _10_ (watch) TV, but sometimes she talks with her mother . She goes at about 10:00.
五.完成句子
1. I have two ____________. ( knife)
2. Whose ______________ are these ? ( child )
3. These photos are hers. They are not ____________. (I)
4. What about ____________ shopping? (go)
5. The little girl is ____________ on her hat now. (put)
6. The man is opening the door. He isn't _________________ the door. (open 的反义词)
7. What is the teacher doing? He is ____________(write) the words on the blackboard.
8.There ____________ some bananas in the bag. (be)
9. Lucy and Lily can speak a little ____________. (China)
10. Is it ____________________ to make cakes? (hard 的反义语)
11. There is little f____and drinks in the fridge. Let's go shopping.
12. He is good at swimming in r ___and lakes.
13. Do you have enough m ___to buy a new computer?
14. The last day of the week is S ___ .
15. We must help each other and I ___from each other.
六.补全对话
a
A: Where is my pencil?
B: I don't know. Is it ____ your bag?
A: No, it isn't
C: Here is ____ pencil. Is it your pencil?
A: Is it blue?
C: Oh, sorry ,it is red.
A: Thank you all the same. My pencil is blue.
B: Here is ____pencil. It's ____ the floor. _____the chair.
A: Oh, it is my pencil. Thank you very much..
B and C: That's alright .
b
A：Hello !
B： 1 !
A：What 2 3 name?
B： 4 name 5 Jim Green .
A： 6 are you ?
B：Fine, 7 you. 8 you?
A： 9 fine, 10 .
c
A: Hello!Mike!
B: Hello!Kate!
A: _______ 1_______ 2 are you?
B: I'm twelve. Are you twelve, too?
A: No, I'm eleven.
B: _______ 3_______ 4 are you in?
A: I'm in Class Two.
B: I'm in Class Three.
A: Class Three? Ann is in Class Three, too.
B: Ann? _______ 5 Ann?
A: She is my friend. Look! She is over there. This_______ 6 , please.
B: Thanks.
A: Hello! Ann!
C: Hello! Kate!
A: Ann, _______ 7 is Mike.
C: Nice to meet you.
B: Nice to meet you, too.
A: Ann, Mike and you are in the _______ 8 class.
C: Oh? Are you in Class Three, Mike?
B: Yes.
C: Good.
A: Excuse me.
B: _______ 9 ?
A: What's the _______ 10 , please?
C: Oh, it's eight thirty. Let's go to the classroom.
七.书面表达
给你的朋友写一封信,并告诉他你的学习情况,字数在50字左右.



参考答案
一.1. A 2. D 3. C 4. B 5. D 6. A 7. B 8. B 9.C 10. B 11.C 12. B 13.D 14.C 15.D 16.C 17.B 18.C 19.D 20.D
二. 1. C 2. A 3. B 4. B 5. C 6. D 7. B 8. A 9. D 10. C
三. B C A B B T T F F T B A C D D
四.1.gets 2..has 3.goes 4.gets 5.doesn’t like 6.has 7.plays 8.flies 9.gets 10.watches
五、1. knives 2. children 3. mine 4. going 5. putting 6. opening 7. writing 8. are 9. Chinese 10. easy 11. food 12. rivers 13. money 14. Saturday 15. learn
六. 1. in, a, a, on, under
2. Hello is your My is How thank And I’m too
3.How old What class Who's way this same Yes time
七.略

我在青年人专业英语四八级考试网看到他家有题呢 你可以去看看

1 D. ; a hair不可数 beard可数 a beard一把胡子2 A how exciting 感叹句,省略了it is3 B at what 这题是宾语从句,千万不要理解错定语从句因为这题没有先行词,不是定语从句,而是介词at的宾语从句at what we thoug...

熊猫生活在四川 西南 所以是c
in threes 是固定搭配 每三个一组
leave for……离开某地去哪里 这里的home可能是副词 就像go home一样 maybe~
water在这里是动词 既然是原型 那就是to do sth with doing sth
on the internet 固定搭配 在网上= online
selling there be后面所跟句子中的动词都是ing形式

1B 2C 3D 4C 5B 6A 7C 8D 9B 10B 11A
多选题1ABC 2ABC
仅是个人观点，供参考

你很好学呀,你的这个是搜来的吧.应为没人会打开头那些可有可无的程序.
倒数第三行可知f数组是包含最大可以获得的奖品价值（也就是快排找最大）
c数组自然就是放每两级的值来做排序的比较和来存f数组最优.
支持原创!抄袭的不得好死!

新华书店

a1=100,an=100q^(n-1)≤1000,2^(n-1)≤10,n-1≤log2(10);
n≤[log2(10)]+1,n=4;
100,200,400,800

http://wenku.baidu.com/view/8cc9104133687e21af45a988.html

Vo = - (Vis1 * Rf / R2 + Vis2 * Rf / R3)
字不清楚,从上到下 ：R1、R2、R3 .

When is his birthday?他什么时候生日?
He doesn't enjoy playing basketball. 他不喜欢打篮球.
Do you often clean the room on Friday?你们经常在周五打扫房间吗?

这是长春市数学的教研员于海洋老师自己编的题。

直线方程可化简为：kx-y+√2=0
将其带入圆的方程：x^2+y^2=4 可得：（k^2+1）x^2+2√2kx-2=0
设A（x1,kx1+√2） B(x2,kx2+√2) 则x1+x2=-2√2k/(k^2+1)
设M（x,y）则向量AM=（x-x1,y-kx1-√2） OB=(x2,kx2+√2)
因为两向量相等
所以{x-x1=x2 解得：{x=-2√2k/(k^2+1)
y-kx1-√2=kx2+√2 y=2√2/(k^2+1)
将M代入圆的方程,解得：k=±1

D 恩格尔系数是用来衡量生活水平而非收入水平的。
1857年，世界著名的德国统计学家恩思特(恩格尔阐明了一个定律：随着家庭和个人收入增加，收入中用于食品方面的支出比例将逐渐减小，这一定律被称为恩格尔定律，反映这一定律的系数被称为恩格尔系数。其公式表示为：
恩格尔系数（%）= 食品支出总额 /家庭或个人消费支出总额×100%...

是氧化性盐没错,.但是跟物质组成有什麽关系?你能从Na,Cl,O元素中看得出是氧化性盐?

c
甲是突触结构,单向传递.前后没有电信号的传播.不发生偏转
乙在神经纤维上,电信号先经过左侧,偏转,再经过右侧,偏转.共两次偏转.方向相反

选D
A 经脱分化形成愈伤组织
B培养病毒应用活的细胞,如活的鸡胚细胞
C青霉素本身就是青霉菌产生的,不属于基因工程范围.
D 正确 .这2个工程都能将2个不同物种的遗传性状组合中一起.

选C
肌糖原不能直接分解为葡萄糖,只能经过糖酵解生成乳酸,通过血液循环的运输再在肝脏中将乳酸转化为葡萄糖等,间接地来维持血糖的浓度.

淡黄色沉淀是硫.
A、能共存,加入NaClO可以把硫离子氧化成硫,加盐酸不行.
B、 H+ S2- NO3-不能共存.
C、 Ca+ S2- SO32-不能共存.
D、能共存,加入NaClO可以把硫离子氧化成硫,加盐酸：2S2- + SO32- + 6H+=3S+3H2O.

说起小麦,其实“小麦”,其实是小麦属若干物种的统称.
我不知道题目中的若干品种是否属于同一物种,但从答案来看似乎不是.

在等腰梯形ABCD中,AB=2DC=2,∠DAB=60 E为AB的在中点,将三角形ABC和三角形BEC分别沿ED,EC向上折起,使A,B点重合于点P,则三棱锥P-DCE的外接球的体积为?
答案
见这里,http://zhidao.baidu.com/question/95552719.html
把它放到正方体里去
设四面体的棱长为a易知正方体棱长=四面体棱长/√2=a/√2
他们的外接球相同
半径为正方体体对角线的一半
故半径r=(a/√2)*√3/2=√6a/4

ADP合成为ATP在ATP合成酶上,ATP合成酶在类囊体膜的叶绿体基质侧.
氧气产生于放氧复合体对水的催化分解,放氧复合体在类囊体膜的类囊体腔侧.
CO2的固定和还原发生在叶绿体基质中
高能电子传递发生在类囊体膜上.
所以答案是B

建议以后还是把题目发上来,否则像你现在这样提问是不可能得到解答的.

人教七年级数学(上)第一章有理数1.1.3单元检测试卷
一、判断题 （每题1分,共8分）
1．如果海拔1200 m表示高于海平面1200 m,那么海拔―150 m表示低于海平面―150 m .（ ）
2．有理数分为正数和负数.（ ）
3．任何有理数的绝对值都是正数.（ ）
4．有理数都有倒数.（ ）
5．－ 不一定是负数.（ ）
6．两个负数,绝对值大的反而小.（ ）
7．两个有理数的和一定大于加数.（ ）
8．一个数a的绝对值是4,则a＝4 .（ ）
二、填空题 （每空1分,共27分）
1．如果节约10度电记作+10度,那么浪费15度电记作 度.
2．把下列各数填入它所属的集合内
2,―3,―0.56,+11,,0.618 ,―125,+2.5,― ,―2.333,0 .
正数集合{ } 负数集合{ }
整数集合{ } 正分数集合{ } 负分数集合{ }
3．最小的正整数是 ,最大的负整数是 .
4．某种零件,标明要求是φ20±0.02 mm（φ表示直径,单位：毫米）,经检查,一个零件的直径是19.9 mm,该零件 （填“合格” 或“不合格”）.
5．数轴上与原点的距离是1.5的点有 个,这些点表示的数是 ；与表示数1的点距离等于3的点表示的数有 个,这些点表示的数是 .
6．一个数a的绝对值就是数轴上表示数a的点到 的距离.
7．― 的相反数是 ,倒数是 ,绝对值是 .
8．化简：－（＋0.7）＝ ,－（－ ）＝ ,－（－11）＝ .
9．已知a,b,c在数轴上的位置如图1-1,用“＜”或“＞”连接
则a－b 0 ,a＋c 0 ,b c ,.c b 0 a
图1-1
10．比较大小：－ － ,.
11．某日的最低气温是零下4°C,最高气温是零上5°C,这天的温差是 .
三、选择题 （每题3分,共21分）
1．数轴上点A表示－4,点B表示2,则表示A、B两点间的距离的算式是 （ ）
（A）－4＋2 （B）－4－2 （C） 2―（―4） （D）2－4
2．已知有理数a大于有理数b ,则 （ ）
（A）a的绝对值大于b的绝对值 （B）a的绝对值小于b的绝对值
（C）a的相反数大于b的相反数 （D）a的相反数小于b的相反数
3．高度每增加1千米,气温就下降2°C,现在地面气温是10°C ,那么7千米
高空的气温是 （ ）
（A）—14°C （B）—24°C （C）—4°C （D）14°C
4．已知两个有理数的和比其中任何一个加数都小 ,那么一定是 （ ）
（A）这两个有理数同为正数 （B）这两个有理数同为负数
（C）这两个有理数异号 （D）这两个有理数中有一个为零
5．计算 是应用了（ ）
（A）加法交换律 （B）加法结合律
（C）分配律 （D）加法的交换律与结合律
6．若｜a+b|＝-（a+b）,下列结论正确的是（ ）
（A）a+b≤0 （B）a+b0
7．下列说法正确的是( )
（A）-a一定是负数; （B）│a│一定是正数; （C）│a│一定不是负数; （D）-│a│一定是负数
四、计算题 （每题4分,共24分）
1． （－10）＋（＋7） 2． （－8）－6
3． 12－（－18）＋（－7）－15 4． 5.6＋（－0.9）＋4.4＋(－8.1) ＋(－0.1)
5． 6．
1．（5分）某班10名学生在一次数学测验中的成绩以90分为标准,超过的分数记为正数,不足的分数记为负数,记录如下：
－7,－10,＋9,＋2,－1,＋5,－8,＋10,＋4,＋9
求他们的平均成绩.
2．（5分）一天,甲乙两人利用温差测量山峰的高度,甲在山顶测得温度是 －1ºC,乙此时在山脚测得温度是5ºC,已知该地区高度每增加100米,气温大约降低0.6ºC,这个山峰的高度大约是多少米?
3．（10分）检修组乘汽车,沿公路检修线路,约定向东为正,向西为负,某天自A地出发,到收工时,行走记录为(单位:千米):
+8、-9、+4、+7、-2、-10、+18、-3、+7、+5
回答下列问题:(每题5分,共10分)
(1)收工时在A地的哪边?距A地多少千米?
(2)若每千米耗油0.3升,问从A地出发到收工时,共耗油多少升?
附加题：（10分）观察下面一列数,探究其中的规律：
—1,,,,,
（1） 填空：第11,12,13三个数分别是 ,,；
（2） 第2008个数是什么?
（3） 如果这列数无限排列下去,与哪个数越来越近?

有点难度
显然,a>0,原不等式的解决集合为1+a/2

首先路程差是500m 速度换算v1=20m/s v2=10m/s,速度差10m/s,刹车的列车应该是匀减速直线运动,不撞上的条件就是后车走过500m是两车速度至少相等,即速度差为0,所以此题等同于500m路 初始速度10m/s,要求最终在500m处速度为0
（v1^2-v2^2）/2a=500 a=0.3m/s^2

这种试题是找不到了．．．网上没有
请采纳答案,支持我一下.

4｜6^n-2^n,4｜3^n＋1,
所以 4｜6^n-2^n-3^n-1,
3｜6^n-3^n,3｜2^n+1,
所以 3｜6^n-3^n-2^n-1,
5｜6^n-1,5｜3^n+2^n,
所以 5｜6^n-1-3^n-2^n．
由于4,3,5两两互质,所以
60｜6^n-3^n-2^n-1．

设（2000-a)=x.
﹙1998－a﹚=y
那么xy=1999,x-y=2
所以﹙2000-a﹚²＋﹙1998－a﹚²=x²+y²=(x-y)²+2xy=4+2*1999=4002

对函数求导：
y'=e^x-a
（1）当a≤0,y'＞0故函数恒为增函数,
单调递增区间为（-∞,+∞）
（2）当a>0,y'>0得x>lna
函数单调递增区间为（lna,＋∞）
单调递减区间为（-∞,lna）
——戴氏高升桥校区数学王老师真诚向您解答
高升桥罗马假日广场加了楼三楼

“摘”一定是从已有的文字材料中摘,离开文字材料,谈不上“摘”.所以,要表示从现有文章中选择重要内容,用“摘要”是最合适不过的.
“择要”不限于从文字材料中选择,因此,既可以说择要刊登,也可以说择要介绍、择要简述、择要罗列等.
第二个问题显然要说“择要回复”,但第一个我认为两可.不管你们老师怎么坚持用“摘要”,其实两个都合适.当然,人们通常会使用“摘要刊登”,这样的例子更多.
需要注意的是,“择要”似乎比“摘要”的意思复杂,“摘要”应该是从一个完整的文字材料中选取一部分,而“择要”除了这个意思外,还可以有从众多个材料中选取若干个的意思.

An=|3n-10|
A1=7,A2=4,A3=1,当n>=4,An=3n-10
Sn=7n-(3/2)n*(n-1)=-(3/2)n*n+(17/2)n,n3

1、A,C
2、A,D
3、A,D
4、C
5、C

works isn't sells are asks speaks sitting talking listening he

不懂就别乱说,可以,第一问我就不想说了,第二问二面角A-DE-C可以分为A-DE-B 和 B-DE-C.这个懂咯.二面角可以通过面积法来求.易证C点在面BDE的投影为B点.而cos(B-DE-C)就等于面积BDE除以面积DEC.同理在BD中点F就是A点在面BDE上的投影.至于面积怎么算可能要用余弦和正弦定理.我高考就喜欢用传统方法解题,因为用起来方便,坐标法太局限.这题如果不熟悉的话,你就用坐标法吧,因为有个现成的坐标系.

第一次,整体漂浮 F浮=G盒+ρ金V金g=ρ液gs2h1
第二次,整体漂浮 F浮=G盒+ρ金V金g=ρ液g(s2h2+V金)
联列二式得到V金=S2(h1-h2)
第三次,剪断后,盒子漂浮,金属块沉底(浸没)
F'浮=G盒+ρ液V金g
用第一次和第三次浮力式子得
底部减小的压强P=(F浮-F'浮)/S1
=(ρ金V金g-ρ液V金g)/S1
=(ρ金-ρ液)V金g/S1
==(ρ金-ρ液)g(h1-h2)S2/S1

鸟嘌呤G占20%,那么C=G=20%*400
A和T一共有1-C-G=60%*400
A=T,所以A=T=30%*400=120
所以A-T碱基对有120对,选B