八年下册物体题!请详细回答如图所示,三个质量相同,底面积相等但形状不同的容器放在水平桌面上,其内装有深度相同的同种液体,

∵ ∠A=36°,∠C=2∠A
∴ ∠C=72°,∠ABC=72°
∴ ∠C=∠B
∴ AB=AC
又∵ BE平分∠ABC,
∴ ∠ABE=∠CBE=1/2∠ABC=36°
∴ ∠ABE=∠A,即BE=AE.
又∵ ∠C=72°,∠CBE=36°
∴ ∠BEC=72°,∠C=∠BEC.∴BC=BE.
又∵BC+CE+BE=12cm,CE=2cm.
∴ BC=BE=5cm.
又∵BE=AE=5cm,AE+CE=AC
∴ AC=5cm+2cm=7cm.
又∵AB=AC
∴ AB=AC=7cm

饮酒
陶渊明
结庐在人境,而无车马喧.
问君何能尔,心远地自偏.
采菊东篱下,悠然见南山.
山气日夕佳,飞鸟相与还.
此中有真意,欲辨已忘言.
行路难（其一）
李白
金樽清酒斗十千,玉盘珍羞直万钱.
停杯投箸不能食,拔剑四顾心茫然.
欲渡黄河冰塞川,将登太行雪满山.
闲来垂钓坐溪上,忽复沉舟梦日边.
行路难!行路难!多歧路,今安在?
长风破浪会有时,直挂云帆济沧海.
还有杜甫《茅屋为秋风所破歌》,岑参《白雪歌送武判官归京》,龚自珍《己亥杂诗》
自己查一下,累死我了!

①作为裁判应主持公道，公平执哨，充分理解同学们求胜的心情。避免和弄清误判，及时改正。
②作为同学们来说，裁判因没看清误判，也是情有可原的，我们要有宽广的胸怀和理智的行为。公平是相对而言的，绝对公平是不存在的。为观众献上一场精彩比赛，活跃同学们课余生活比什么都重要，弃球罢赛的做法是不可取的，并且对其他球队来讲也是不公平的。

利息：3000x6.2%x8
=186x8
=4488(元)
本息：3000+1488=4488（元）

我有要上册的还是下册的

剪不断的“脐带"
多角度看母爱
报得三春晖

要么你的樱桃树是没有嫁接的实生苗,要么就是你的养护管理有问题.
樱桃结实需要的管理比较简单,但必不可少.你参考一下：
提高樱桃产量和质量,可通过整形修剪、疏花、疏果等措施来调控产量和质量：
1、整形修剪主要树形采用纺缍树形,干高0.4-0.5 米、树高2.5-3.5 米.中心干上,轮生 15-25 个主枝单轴延伸、角度近水平、不分层次的主枝,除了下部3 个主枝可着生 2-3 个侧枝外,其余主枝上直接着生结果枝组,不培养侧枝.此树形可使 树 体 枝 量 迅 速 增 加 ,立 体 结 果 能 力 强 ,群 体效益高.夏季修剪摘心,促进幼树花芽分化：轻度摘心（摘去顶端5 厘米左右）：能发 1-2 个新梢,然后再对发出的新梢留 15 厘米左右连续摘心后能形成结果枝；中度摘心（新梢长到40厘米时摘去顶端 15厘米左右）：能萌发3-4个分枝,并形成结果枝；重度摘心（新梢长到40 厘米以上时,留 15厘米左右摘去顶端）：能促进萌发分枝,还能使下部形成短枝或叶丛枝,形成小结果枝.扭梢、拿枝：扭 梢 就 是 在 半 木 质 化 时 对 生 长 旺 盛 的 徒长枝、竞争枝扭转180 度,削弱其长势,促进花芽分化,改造成结果枝组；拿枝就是将强旺枝、徒长枝用手自基部向上挪动,伤及木质部而不折断,抑制生长,改变角度,促进花芽形成.结果枝组的培养：在生长季节进行扭梢或重度摘心,然后缓放 ,能 培 养 形 成 紧 奏 型 小 结 果 枝 组 ；用 轻 度 摘心 和 轻 短 截 的 方 法 能 培 养 成 单 轴 式 小 型 结 果枝组；冬季中短截和夏季中度摘心能培养形成大中型结果枝组.另外,6-7 月份用多效唑进行叶面喷施,也可抑制枝梢旺长、促进花芽分化.
2、疏花结合冬季修剪 ,剪去下垂枝、细弱枝及连续结果多年的结果枝组；在花蕾期剪除过多、弱小花芽及发育差的弱小花蕾和畸形花蕾；开花后疏去双子房的畸形花、弱质花.每个花序上可保留1-2 朵花.
3、疏果疏果是在疏花的基础上进行的,时间一般在生理落果后进行.疏果原则：壮树强枝多留、弱 树 弱 枝 少 留 ；疏 果 顺 序 ：先 里 后 外 、先 上 后下.疏除对象为弱小果、畸形果、病虫果、授粉受精不良及弱枝上的过多果.

这个看着书很好分辨的.只要看到有练习题了.就算是一个课时.就按这个方法.是一定可以上完的.不会影响期末复习的.数学课不好图快的.快了效果不是很好.当然你也可以根据你的学生实际情况来合理选择也是可以的.一般情况下都是一个练习是一个课时.

Question of lotus leaf's mother:
Read this two paragraphs carefully-"Eight years long"and "The moon night of nine years earlier",and taste the author's feeling

第2句,“保持写日记的习惯”改为“养成写日记的习惯”
第4句,“以前”和“旧”重复,删去任意一个
第8句,“并且”改为“但是”,与前面的虽然搭配

1/（1*2)=1-1/2 1/（2*3)=1/2-1/3 1/（3*4）=1/3-1/4 后面依次类推…… 最后一项 ：1/（3000*3001）=1/3000-1/3001第二项和第三项消去，第四第五项消去，…… 最后只剩下第一项和最后一项即1-1/3001=3000/3001

八年来您为我们花了很多的心血,给了我们无尽慈母般的温暖.

还有九十中我们六十二嗯先确定介绍哪中介绍你们中学特点文化再介绍项日目用记者的口气采访你的班级嗯你介绍你们班再介绍参赛的人什么活动好的心情`心里活动你参加了什么获得什么奖名次嗯今后会努力开头最好介绍运动的好处哦了和由来会了吗嗯好吧去写吧...

The train is leaving soon(同义句）
1.The train_is__ _going___ __to___ __leave__soon.
2.The train_will___ __leave__soon

愤怒,她有什么资格这样说

平型关大捷、百团大战、多次反围剿

“潭中鱼可百许头,皆若空游无所依.日光下彻,影布石上,然不动；尔远逝,往来翕忽.似与游者相乐.”
这是一幅极美的画面.在水中游动的鱼儿,不像是在水里,而是像在空中游动.太阳光照下来,鱼儿的影子落在了潭底的石头上.从字面上看,作者是在写鱼,但透过字面,却令我们不能不对那清澈的潭水留下极深的印象.这种游鱼和潭水相互映衬的写法,收到了很好的艺术效果.然后,作者进一步对鱼儿进行描述.先是鱼儿呆呆地一动不动,忽然,有的鱼飞快地窜向远处,一会儿游到这儿,一会儿又游到那儿,好像是在与游人一同享受着快乐.读到这里,我们不能不从游鱼联想到作者的欢悦心情.这种由情入景,由景及情的写法正是这篇散文的一个突出特色.

不是比喻句,本体和喻体不能是同一种事物.这里是把老师的温暖比作慈母的温暖,就像不能说 ‘’我长得像妈妈‘’是一个比喻句一样.这只是个人见解...

建议以后还是一题一题的把题目发上来,否则像你现在这样提问是不可能得到解答的.

900万.因为八年的本利和是4400万.你交了七年一共3500万,还差九百万

对免疫系统的作用像是在调整音量,使其处于最佳状态

已知一段高速公路长2米,现需要翻修,甲施工队单独修完需要八年,乙施工队单独修完需要十年,现在两个施工队从两端同时动工,大约多久修完?4到5年

1.as the same as 是固定搭配
2.不行,否定两者就用neither
3.前者表示的含义是“首先,开始的时候”,后者也有这些含义,但是后者还可以用作别的意思,比如“先.样.”举个例子说明一下吧.比如你跟朋友约好了去踢球,可是你中途有事会晚到一会,你打电话告诉他们你会晚到一会,让他们先玩.这时你可以说,“you can paly first!”意思就是“你们先玩吧,不用等我到了再玩.”

sailors,sailing
most
she aked us not to imagine...
...my favorite singer who will have an interview...

不对.
白炽灯发出的光不是平行光,建议使用太阳光
如果没有太阳光,可以使用远景成像法：
1.把白炽灯远离透镜
2.移动光屏,直至光屏上出现远处白炽灯清晰的缩小的像
3.测量光屏和光心的距离,即焦距

《论语十则》
1.子曰：“学而时习之,不亦说乎?有朋自远方来,不亦乐乎?人不知而不悦,不亦君子乎?”
1.孔子说:"学习了(知识),然后按一定的时间去实习(温习)它,不也高兴吗 有志同道合的人从远处(到这里)来,不也快乐吗 人家不了解我,我却不怨恨,不也是君子吗 "
2.曾子曰:"吾日三省(xǐng)吾身:为人谋而不忠乎 与朋友交而不信乎 传不习乎 "
2.曾子说:"我每天多次地反省自己:替别人办事是不是尽心竭力呢 跟朋友往来是不是诚实呢 老师传授的学业是不是复习过呢 "
3.子曰:"温故而知新,可以为师矣."
3.孔子说:"在温习旧知识后,能有新体会,新发现,凭借这一点就可以当老师了."
4.子曰:"学而不思则罔,思而不学则殆."
4.孔子说:"只读书却不思考,就会迷惑而无所适从;只是空想却不读书,就会有害.
5子曰:"由,诲女知之乎!知之为知之,不知为不知,是知也."
5.孔子说:"由,教给你对待知与不知的态度吧:知道就是知道,不知道就是不知道,这就是聪明智慧."
6.子曰:"见贤思齐焉,见不贤而内自省也."
6.孔子说:"看见贤明的人,要想着向他看齐,看见不贤明的人要反省有没有跟他相似的毛病."
7.子曰:"三人行,必有我师焉;择其善者而从之,其不善者而改之."
7.孔子说:"几个人同行(在一起),其中必定有我的老师,我要选择他们的长处来学习,看到自己有他们那些短处就要改正."
8.曾子曰:"士不可以不弘毅,任重而道远.仁以为己任,不亦重乎 死而后已,不亦远乎 "
8.曾子说:"士人不可以不胸怀宽广,意志坚定,因为他肩负着重大的使命,路程又很遥远.把实现'仁'的理想看作自己的使命,不也很重大吗 到死为止,(路)不也(走得)很遥远吗 "
9.子曰:"岁寒,然后知松柏之后凋也."
9.孔子说:"(碰上)寒冷的冬天,这以后(才)知道松柏树是最后落叶的."
10.子贡问曰:"有一言而可以终身行之者乎 "子曰:"其恕乎!己所不欲,勿施于人."
10.子贡问道:"有没有一句可以终身奉行的话 "孔子说:"那大概是'恕(道)'吧!自己所讨厌的事情,不要施加在别人身上."

题目在哪？不是每个想回答你的人都有那本书呦

根据概率公式知,共有48名团员,从中随机选择了12名团员,李明能参加这次活动的概率是1/4 ．

Hello,I'm a reporter from Class12,Grade8.Now we are having a class meeting with the topic 'advantages and disadvantages for using mobil phone in school'.Some of my classmates think it is very usful and convenient using mobil phone to refer to dictionary,moreover,it really helps to develop listening of English if we frequently listen to the MP3 read by native speakers which could be downloaded from internet and sync to phone.In the other hand,students have mobile phone would be easily found by their parents.However,the advocates are againt by some other students who disagree that mobile phone helps to study but brings ruin to someone.For example,some students think using mobile phone in school is fashionable and always play with it,what's more is sending or recieving messages in class also it could be used to copy answers during exams.
As for my opinion,I would like to say every advantage has its disadvantage and whether the use of mobile phone to be allowed in schoole is hard to draw a conclusion.That apparently depends on you yourself.You can choose the right way or the wrong way,it is you to make decision!How you use it results in conclusion!
最好再拼写检查一下哦^-^

How are you going to do it?怎么做?
What are you going to do?做什么?
become为系动词,系动词一般都是固定的,只要记住特殊的时候的用法就ok了

哪个题

写日记的一个好处是能记录自己成长中的点点滴滴.我保持
写日记的习惯已经八年了.这厚厚的一摞日记本是我的财
富.偶尔翻看以前的日记,我感触很多.虽然日记里不乏无病
呻吟,也有不少狂妄的长篇大论,但更多的是对平凡生活
的感受,对自我的反省和鼓舞.

化学你们初3每个人都是第一次接触的,所以来说每个人的基础是一样的,我觉的化学不难的呀,平常课堂认真听讲,联系做一就OK的,只要上课老师讲的内容你都弄明白了,那就没什么问题咯,很简单的哦.加油咯.

土地是大自然的基础,世间万物依托土地而存在,人类在土地上繁衍生息.土地承载着人类社会对历史的回顾、对现状的建设和对未来的憧憬.
这首诗抒发了作者感谢土地、热爱土地、敬仰土地的情感.

个人觉得悬C
A德高望重指道德高尚,名望很高.一般形容长者、有名望的人
B苦心孤诣有点贬义,不适合
D小题大做比喻把小事当作大事来办,有不值得这样做或有意扩大事态的意思. 不符合语境.

初二英语（下）期末测试卷
二、单项选择题：
1. Mr. Brown taught __________ English last term.
A. our B. us C. we D. ours
2. Is there ___________ in today’s newspaper?
A. anything interesting B. interesting anything
C. something interesting D. interesting something
3. I thought ________ to find a Chinese restaurant
A. it is easy B. it easy C. its easy D. that easy
4. Either Kate or I _______ right.
A. is B. are C. am D.do
5. There is a café ______ the end of the road.
A. at B. in C. on D. to
6. The station is 2 kilometers ________ my home.
A. far from B. far away C. away from D. far
7. Her husband is ill _____
A. in a hospital B. in hospital C. in the hospital D. on the hospital
8. You ________ late again.
A. had not better be B. had better not be C. had better be not D. had better not to be
9. ---What’s wrong with the watch? ---_______
A. It doesn’t matter B. It doesn’t work C. It’s all right D. It’s wrong
10. My father is on _______ way ________ the hospital
A. his, of B. his, for C. the, of D. the, to
11. Lucy can swim ________
A. So I can B. I can so C. So can I D. So do I
12. Lucy goes to school on foot. __________
A. So is Lily B. Lily does so. C. Lily is so D. So do I
13. The students stopped _________ when the teacher came in.
A. talking B. talked C. to talk D. talk
14. He didn’t think you were right, ____________ ?
A. didn’t he B. weren’t you C. did he D. were you
15. --- “Tom, it’s your turn. ” --- “__________________”.
A. So it does B. So it is C. So does it D. So is it
16. There’s only one ticket. __________ you _________ he can go to the cinema.
A. Neither…nor B. Either…or C. Neither…or D. Either…or
17. When did he ________ ?
A. get B. reach C. arrive D. get to
18. ---Would you please help him with his maths? --- “____________”
A. Not problem B. No problem C. Not problems D. No problems
19．The doctor looked _________ the sick girl carefully and gave her some medicine.
A. over B. up C. out D. like
20. This kind of dress looks ________ and sells _______
A. good, good B. well, well C. good, well D. well, good
21. I ________ let him know it as soon as he ________ back.
A. will, will come B. ×, comes C. ×, come D. will, comes
22. ---__________ you have to finish the work now? ---No, I _______
A. Do, don’t B. Don’t, do C. Must, needn’t D. Do, do
23. ---Must I go there now? ---No, you _______
A. mustn’t B. can’t C. don’t D. needn’t
24. She isn’t sure what to do tonight. She _________ go to the cinema.
A. must B. can C. may D. has to
25. Neither of us __________ good at music
A. is B. are C. be D. was
三、完形填空：
Erik was a fourteen-year-old boy. He thought he was a young man but his parents didn’t think so.
They told him, “When you begin to think about 1 others, you’ll be a young man. ”
One morning, his parents gave Erik 2 money to buy hamburgers at a store. He saw an old man
there. The man looked very 3 . Erik went up to him and found that the old man had lost his
money and hadn’t had 4 for his breakfast. Erik took the old man to the nearest restaurant. But the
man ordered only a glass of water for 5 . Erik felt sorry for him, so he asked the waiter to 6
the man some bread and a cup of coffee. The old man was so 7 that he ate up all the food very
soon. After that, the man told Erik that he would never forget 8 kindness. Erik was very pleased
when he heard the old man say, “You are a very good young man. ”
9 their surprise, the food was a present because 10 day was the birthday of the boss.
A B C D
（ ）1. help helping to help helped
（ ）2. a few few some many
（ ）3. sick tried happy fine
（ ）4. something anything everything nothing
（ ）5. themselves herself myself himself
（ ）6. take bring taking bringing
（ ）7. full worried hungry sad
（ ）8. your my her his
（ ）9. For To At On
（ ）10. that this those these
四、阅读理
A
An artist（画家）went to a beautiful place of the country for a holiday, and stayed with a farmer. Every day he went out and painted from morning to evening. When it got back, he came back to the farm and had a good dinner before he went to bed.
At the end of his holiday he wanted to pay the farmer, but the farmer said, “No, I don’t want money but give me one of your pictures. What is money? In a week it will all be finished, but your painting will be here.”
The artist was very pleased and thanked the farmer for saying such kind words. The farmer smiled and said, “I have a son in London. He wants to become an artist. What he comes here next month, I will show him your picture, and then he will not want to be an artist any more, I believe.”
1. The artist liked to _________ near a nice place.
A. sing songs B. dance C. paint pictures D. write something
2. He liked painting ________.
A. in a house C. because he would do well in painting
B. in the open air D. with the most important artist
3. The famer thought that the artist ________.
A. was not good at painting B. was really a great man
C. did well in painting D. was the most important artist
4. The farmer’s son wanted to ________ some day.
A. be an artist B. become a popular singer
C. write twenty novels . D. dance around the world
5. The farmer _________.
A. was a foolish man B. didn’t want his son to be a painter
C. liked the artist’s picture very much D. couldn’t pay for his son about his paintings
B
Miss Evans taught physics in a London school. Last month she was explaining（解释）to one of her classes about sound, and she wanted to know if the students understood it. She said to them, “Now, I have a sister in Washington, I want to call her on the telephone. If you were 20 meters away and listened to me from the other side of the street when I phoned her up, who would hear what I said earlier, my sister or you ----and why?” The cleverest boy at once answered, “Your sister, Miss Evans, because electricity（电） travels faster than sound.” “That’s very good, ”Miss Evans answered; but then one of the girls put up her hand, and Miss Evans said, “Yes, Betty?” “I disagree, ” Betty said. “Your sister would hear you earlier because when it’s eleven o’clock here, it’s only six o’clock in Washington.”
1. Mrs. Evans taught physics at a school in _________
A. Washington B. London C. a town D. the country
2. She wanted her students to know which __________ was faster,
A. herself of her sister B. the boys or the girls
C. sound or electricity D. London or Washington
3. The cleverest boy thought sound was _________ than electricity.
A. faster B. fast C. slower D. slow
4. Miss Evans thought __________ answer was right.
A. the boy’s B. the girl’s C. her sister’s D. the other students’
5. Betty thought the cleverest boy was wrong, because _______
A. clocks in Washington showed a different time from those in London
B. electricity is slower than sound C. electricity travels as fast as sound
D. electricity is faster than sound
C
Beethoven（贝多芬）was never afraid to show his feelings. One when he was playing at a rich man’s
house, one of the listeners, a man of good family, was talking to a girl. He liked girls more than music,
and he didn’t stop talking when Beethoven started to play. The voice was not a quiet one, and
Beethoven could hear well in those days. The music stopped in the middle and Beethoven stood
up. “I don’t play for animals of this kind!” he cried. “No! Not for animals!” Then he walked out.
1、Beethoven was a ______
A. painter B. musician C. chemist D. singer
2、The listener was ______
A. from a poor family B. rich C. an old man D. a child
3、One of the listeners _________ when Beethoven started to play.
A. listened carefully B. stopped talking C. still talked to a girl D. sang loudly
4、This listener ________
A. didn’t like music B. liked both girls and music
C. liked music more than girls D. was more interested in girls than in music
5、Beethoven ________ after he heard their talking
A. went on playing B. stood up and left C. was happy D. talked with them
五、补全对话：
D: What’s the __________, young lady?
W:I feel very weak. I cannot do any work, doctor.
D: Do you _________________________?
W: No, I don’t have a headache.
D: ______________________ at night?
W: Yes, I sleep very well.
D: Do you ____________________ every morning?
W: No, I don’t have breakfast. And I have only a little food for lunch and supper ___________
I want to keep_____________________
D: Oh, I see. There’s nothing _____________. You need to eat _____________food and have ____________meals a day. And do some _____________ every day. Then you’ll get better soon.
六、书面表达：
如果你（Tom）有一个笔友（Mark）经常生病,请给他写一封信,给他一些好的建议.

参考答案
二、单项选择：
1—5：B A B C A 6—10：C B B B D 11—15：C D A C B
16—20：B C B A C 21—25：D A D C A
三、完形填空：
1—5：B C A B D 6—10：B C D B A
四、阅读理
1—5：C B A A B 6—10：B C C A A 11—15：B B C D B
五、补全对话：
1 mater/trouble 2. have a headache
3. Do you sleep well 4. have breakfast
5. because 6. thin/thinner
7. wrong（with you）/serious 8. more/enough
9. three 10. exercise
六、书面表达：
Dear Mark:
Thank you for you last letter. I’m sorry to hear that you are often ill. If you try to do the follow things. I’m sure you’ll be better soon.
First of all, you should take more exercise. It’s good for you health. You can play basketball, run, swim and some other sports. Eating healthily is very important. You’d better have more fruit and vegetables. You can drink more milk and water. Don’t eat too much rich food. You must get enough sleep. You should go to bed early and get up early, too. Do as what I say. I hope you can get better soon and stay happy.
Yours
Tom

中英语不规则动词过去式、过去分词表
初中英语不规则动词过去式、过去分词表
（1） AAA型（动词原形、过去式、过去分词同形）
cost（花费） cost cost cut（割） cut cut
hit（打） hit hit hurt 伤害） hurt hurt
let（让） let let put（放） put put
read （读） read read
(2) AAB型（动词原形与过去式同形）
beat（跳动） beat beaten
(3) ABA型（动词原形与过去分词同形）
become（变成） became become come（来） came come
run（跑） ran run
(4) ABB型（过去式与过去分词同形）
dig（挖） dug dug get（得到） got got
hang（吊死） hanged hanged hang（悬挂） hung hung
hold（抓住） held held shine（照耀） shone shone
sit（坐） sat sat win （赢） won won
meet（遇见） met met keep （保持） kept kept
sleep（睡） slept slept sweep（扫） swept swept
feel（感觉） felt felt smell（闻） smelt smelt
leave（离开） left left build（建设） built built
lend（借出） lent lent send （传送） sent sent
spend（花费） spent spent lose （丢失） lost lost
burn （燃烧） burnt burnt learn（学习） learnt learnt
mean（意思是） meant meant catch（抓住） caught caught
teach（教） taught taught bring（带来） brought brought
fight （战斗） fought fought buy（买） bought bought
think（想） thought thought hear （听见） heard heard
sell（卖） sold sold tell（告诉） told told
say（说） said said find（找到） found found
have/has（有） had had make（制造） made made
stand（站） stood stood understand明白understood understood
(5) ABC型（动词原形、过去式与过去分词三者不同形）
begin（开始） began begun drink（喝） drank drunk
ring（铃响） rang rung sing （唱） sang sung
swim（游泳） swam swum blow（吹） blew blown
draw （画） drew drawn fly（飞） flew flown
grow（生长） grew grown know（知道） knew known
throw（投掷） threw thrown show（出示） showed shown
break（打破） broke broken choose（选择） chose chosen
forget（忘记） forgot forgotten (forgot) speak（说,讲） spoke spoken
wake（醒） woke woke drive（驾驶） drove driven
eat（吃） ate eaten fall（落下） fell fallen
give（给） gave given rise（升高） rose risen
take（取） took taken mistake（弄错） mistook mistaken
ride（骑） rode ridden write（写） wrote written
do（做） did done go（去） went gone
lie（平躺） lay lain see（看见） saw seen
wear （穿） wore worn
be ( am,is,are )（是） was,were been
给你一些方法,仅供参考,可以吗?
找那个确实很困难……

解法如下：
设甲图书x套,乙图书y套
45x+40y=500 x+y=12联合一解就出来了
甲图书4套,乙图书8套

小弟愚昧,尝试用a^3+b^3=(a+b)(a^2-ab+b^2)的方法去做
首先(a-b)^2=1,a^2-2ab+b^2=1,因为a^2+b^2=√13所以可计出ab是什么,然后在透过(a+b)^2=a^2+2ab+b^2计出a+b是什么(开方时要分正负号),最后再将计出的数字代进去就计到了.^是次方的意思

这是弦切角定理,

现在还要么

我浏览了很多教育类网站都没有看到相关
你要买这本书是不是?
可以去亚马逊（专业卖书的网站）看一下

这里是心理描写,交代“我”不敢冒险的因,为下文预先埋下伏笔!（老师讲的）希望楼主采纳!

我也是今年初一的学生.我们老师已经强调了.
不光你这一句话,包括那个天气很热,都是为了衬托出作者身体不适,在那种情况下做那种爬山的活动的不容易.

1、AB=3
2、根号13.

由于没图无法确定答案!根据选项答案可以知道ρA>ρ水
猜测图片应该是一种漂浮 一种物质悬浮 A物质沉入水底!