2017年八年级数学下册菱形性质与判定练习题
一选择题：
1.下列四边形中不一定为菱形的是（）
A.对角线相等的平行四边形
B.每条对角线平分一组对角的四边形
C.对角线互相垂直的平行四边形
D.用两个全等的等边三角形拼成的四边形
2.下列说法中正确的是（）
A.四边相等的四边形是菱形
B.一组对边相等，另一组对边平行的四边形是菱形
C.对角线互相垂直的四边形是菱形
D.对角线互相平分的四边形是菱形
3.若顺次连接四边形ABCD各边的中点所得四边形是菱形,则四边形ABCD一定是（）
A.菱形
B.对角线互相垂直的四边形
C.矩形
D.对角线相等的四边形
4.菱形的周长为8cm，高为1cm，则菱形两邻角度数比为（）
A．4：1 B．5：1 C．6：1 D．7：1
5.四个点A，B，C，D在同一平面内，从①AB∥CD；②AB=CD；③AC⊥BD；④AD=?BC；⑤AD∥BC．这5个条件中任选三个,能使四边形ABCD是菱形的选法有（）．
A.1种
B.2种
C.3种
D.4种
6.如图，在菱形ABCD中，AB的垂直平分线EF交对角线AC于点F，垂足为点E，连接DF，若∠CDF=24°，则∠
DAB等于（）
A．100° B．104° C．105° D．110°
7.如图,在长方形ABCD中,AB=12,AD=14,E为AB的中点,点F,G分别在CD,AD上,若CF=4,且△EFG为等腰直角三角形,则EF的长为（）
A.10
B.10
C.12
D.12
8.用一条直线将一个菱形分割成两个多边形,若这两个多边形的内角和分别为M和N,则M+N值不可能是（）
A.360°
B.540°
C.630°
D.720°
9.如图,在周长为12的菱形ABCD中,AE=1,AF=2,若P为对角线BD上一动点,则EP+FP的最小值为（）
A.1
B.2
C.3
D.4
10.如图,点P是矩形ABCD的边AD上的一动点,矩形的两条边AB、BC的长分别是6和8,则点P
到矩形的两条对角线AC和BD的距离之和是（）
A.4.8
B.5
C.6
D.7.2
11.如图,把长方形纸片ABCD折叠,使其对角顶点C与A重合.若长方形的长BC为8,宽AB为4,则折痕EF的长度
为（）
A.5
B.3
C.2
D.3
12.如图,四边形ABCD,AD与BC不平行,AB=CD.AC,BD为四边形ABCD的对角线,E,F,G,H分别是BD,BC,AC,AD的中
点.下列结论：①EG⊥FH；②四边形EFGH是矩形；③HF平分∠EHG；
④EG =（BC﹣AD）；⑤四边形EFGH是菱形.其中正确的个数是（）
A.1个
B.2个
C.3个
D.4个
二填空题：
13.如图,在菱形ABCD中，∠BAD=80°,AB的垂直平分线交对角线AC于点F,E为垂足,连接DF,则∠CDF的度数= 度．
14.如图,正△AEF的边长与菱形ABCD的边长相等,点E、F分别在BC、CD上,则∠B的度数是．
15.把一张矩形纸片ABCD按如图方式折叠，使顶点B和顶点D重合，折痕为EF．若BF=4，FC=2，则∠DEF的度数是．
16.如图,在?ABCD中,对角线AC、BD相交于点O.如果AC=8,BD=14,AB=x,那么x取值范围是．
17.在菱形ABCD中，AE为BC边上的高，若AB=5，AE=4，则线段CE的长为．
18.如图，?ABCD中，AB=2，BC=4，∠B=60°，点P是四边形上的一个动点，则当△PBC为直角三角形时，BP的长为．
三解答题：
19.如图,已知△ABC中,D是BC边的中点,AE平分∠BAC,BE⊥AE于E点,若AB＝5,AC＝7,求ED．
20.如图,在平行四边形ABCD中,用直尺和圆规作∠BAD平分线交BC于点E(尺规作图的痕迹保留在图中了),连EF．（1）求证：四边形ABEF为菱形；（2）AE，BF相交于点O，若BF=6，AB=5，求AE的长．
八年级英语综合填空专项 A Tim spent in a bookshop can be enjoyable. If you go to a good s_______(1) no assistant will come near to you and say, “Can I h_____(2) you？”You needn’t buy a_________(3) you don’t want. You may try to find out whrer the book you want is. But if you w________(4), the assistant will lead you there and then he will go away. It seems that he is not interested i______(5) selling any books at all. There is a story which t________(6) us about a good shop. A medical student found a very useful book in a shop, but it is too expensive for him to b _______(7). He couldn’t get it from the library, e__________(8). So every afternoon he went there to r __________(9) a little at a time. One day, however, he couldn’t find the book from its usual place and was leaving when he saw an assistant signing to him. To his s___________(10), the assistant pointed to the book in a corner, “I put it there so as not to be sold out.” Said the assistant. Then he let the student go on with his reading. B It is well-known that man is much cleverer than any animal. But which is the cleverest a_________(1) the animals? Some scientists t________(2) it should be Alex, an African grey(灰色) parrot. He is unlike any other animal. He can really t ________(3) with people! When he says “come here”, he really w _________(4) someone to come up to him. “Alex is as clever as c ________(5) of 2 or 3 years old,” says Dr. Peter. “He does not just repeat the s __________(6) he has been taught. He u__________(7) the words!” Alex can tell about 50 d__________(8) things, name(叫出) seven colours and count from 1 to 6. Is the parrot actually(事实上) thinking in the w__________(9) how man does? Nobody can say. But the q__________(10) is very interesting. C Obama has a good t________(1) at the Great Wall. He who has never been to the Great Wall is not a t___________(2) man. US President Barack Obama is a true man. Obama had a four-day v_________(3) to China last week. He had a very busy schedule(日程)。But he still s ___________(4) some time visiting the Forbidden City(故宫) and the Great Wall. When a leader visits another c_________(5), he or she sometimes goes to the country’s most f _________(6) places. It is to show respect to the local culture. For rhe leaders, it’s also a good time to r_________(7) during a tiring foreign trip. Obama spent 50 minutes in the Forbidden City on Tuesday. He thinks the Forbidden City is a “magnificent(华丽的) p ________ (8) to visit”. He said: “I will come back with my girls and my wife.” On Wednesday afternoon, he t ________(9) a quick tour of the Great Wall at Badaling. There, he enjoyed a moment of peace. “It’s magical(不可思议的). It reminds(使想到) you o________(10) the sweep(进程) of history,” Obama said about the Great Wall. D Christmas is coming. It’s on December 25. It’s an i_________(1) holiday in many countries, including the US and the UK. Families get t _________(2) to enjoy holiday fun. Santa Claus Legend(传说) say that on Christmas Eve(圣诞节前夕)，Santa comes f_________(3) the North Pole(北极). He d ______(4) his sleigh(雪橇) t o deliver gifts. Kids h_________(5) stockings(长筒袜) on Christmas Eve. On Chirstmas morning, they find g __________(6) in the stockings. Christmas tree People usually u _________(7) a pine tree(松树) for their Christmas tree. In the days before Christmas, kids like to decorate(装饰) the tree. They put c_________(8) lights on the tree. They may also put a big star on the top. The big d_______(9) is everyone’s favorite. Juicy turkey and ham are main dishes. There are also lots of v__________(10) and pies for dessert(甜品). (E) Mr Black worked in an office in London, but he lived in the c________and came to work by train every day. The station was not very f__________ from his office, and Mr Black always went on foot, because he liked w__________. He always walked from his office to the station in the evening too, and he always went along the s__________ street. Every evening he passed a poor man near a bridge. The man sat at the side of the road and sold matches(火柴), and there was always an old dog near him. There was a piece of wood around the dog’s neck, and the words”I Am Blind”were written on the piece of wood. Mr Black was a k___________man. He always stopped, said a few kind words to the poor man, and gave him a little money, but he did not take a___________ of his matches. Then one day , Mr Black had a lot of work in his office and was very late. He said, “My train always leaves at five minutes past sic, and it is ten minutes to six now. I’m not going to talk to the poor man today, and I am not going to give him anything. I have given him a lot of money, and I’ve never taken any of his matches. “He came to the man and his dog, but he did not s_________, and he said n_____________. He walked q___________towards the railway station. But the poor man stood up quickly, ran after him and said , “ You haven’t given me anything today. You’re always very kind to me . Give me a little money today too. I am a poor man.” Mr Black stopped and looked at the man . Then he said “ You are a blind man. H_________ did you follow me?” The poor man said, “ No, I am not blind. My old dog is.” (F) Most people in Poland have their own ways of s__________ free time. Sometimes they just want to have a rest, b__________other times they try to do something more pleasant. They have many different hobbies, which help them to alleviate(减轻)their everyday problems and spend their free time h__________. Many Polish people like t_____________, They
习题14 14.1 选择题 （1）在夫琅禾费单缝衍射实验中，对于给定的入射单色光，当缝宽度变小时，除中央亮纹的中心位置不变外，各级衍射条纹[ ] (A) 对应的衍射角变小． (B) 对应的衍射角变大． (C) 对应的衍射角也不变． (D) 光强也不变． [答案：B] （2）波长nm (1nm=10-9m)的单色光垂直照射到宽度a=0.25mm的单缝上，单缝后面放一凸透镜，在凸透镜的焦平面上放置一屏幕，用以观测衍射条纹。今测得屏幕上中央明条纹一侧第三个暗条纹和另一侧第三个暗条纹之间的距离为d=12mm，则凸透镜的焦距是[ ] (A)2m. (B)1m. (C)0.5m. (D)0.2m. (E)0.1m [答案：B] （3）波长为的单色光垂直入射于光栅常数为d、缝宽为a、总缝数为N的光栅上．取k=0，±1，±2．．．．，则决定出现主极大的衍射角的公式可写成[ ] (A) N a sin=k． (B) a sin=k． (C) N d sin=k． (D) d sin=k． [答案：D] （4）设光栅平面、透镜均与屏幕平行。则当入射的平行单色光从垂直于光栅平面入射变为斜入射时，能观察到的光谱线的最高级次k [ ] (A)变小。 (B)变大。 (C)不变。 (D)的改变无法确定。 [答案：B] （5）在光栅光谱中，假如所有偶数级次的主极大都恰好在单缝衍射的暗纹方向上，因而实际上不出现，那么此光栅每个透光缝宽度a和相邻两缝间不透光部分宽度b的关系为[ ] (A) a=0.5b (B) a=b (C) a=2b (D)a=3b [答案：B] 14.2 填空题 （1）将波长为的平行单色光垂直投射于一狭缝上，若对应于衍射图样的第一级暗纹位置的衍射角的绝对值为，则缝的宽度等于________________． λθ] [答案：/sin （2）波长为的单色光垂直入射在缝宽a=4 的单缝上．对应于衍射角=30°，单缝处的波面可划分为______________个半波带。 [答案：4] （3）在夫琅禾费单缝衍射实验中，当缝宽变窄，则衍射条纹变；当入射波长变长时，则衍射条纹变。（填疏或密） [答案：变疏，变疏]
人 教 版 数 学 八 年 级 下 学 期 期 末 测 试 卷 一、选择题 1.下列方程中，一元二次方程的是（ ） A. 221x x +＝0 B. （2x +1）（x ﹣3）＝1 C. ax 2+bx ＝0 D. 3x 2﹣2xy ﹣5y 2＝0 2.如图，在?ABCD 中，AB ＝6，BC ＝8，∠BCD 的平分线交AD 于点E ，交BA 的延长线于点F ，则AE ＋AF 的值等于( ) A. 2 B. 3 C. 4 D. 6 3.已知一次函数的图象与直线y=-x ＋1平行，且过点（8，2），那么此一次函数的解析式为（ ） A. 2y x =-- B. 6y x =-- C. 10y x =-+ D. 1y x =-- 4.若关于x 的方程x 2﹣2x +m ＝0的一个根为﹣1，则另一个根为（ ） A. ﹣3 B. ﹣1 C. 1 D. 3 5.下列选项中，不能判定四边形ABCD 是平行四边形的是( ) A. AD//BC ，AB//CD B. AB//CD ，AB CD = C. AD//BC ，AB DC = D. AB DC =，AD BC = 6.已知一次函数y ＝（k ﹣2）x +k +1的图象不过第三象限，则k 的取值范围是（ ） A. k ＞2 B. k ＜2 C. ﹣1≤k ≤2 D. ﹣1≤k ＜2 7.某同学五天内每天完成家庭作业的时间（时）分别为2，3，2，1，2，则对这组数据的下列说法中错误的是（ ） A. 平均数 2 B. 众数是2 C. 中位数是2 D. 方差是2
8.甲、乙两队举行了一年一度的赛龙舟比赛，两队在比赛时的路程s （米）与时间t （分钟）之间的函数关系图象如图所示，请你根据图象判断，下列说法正确的是（ ） A. 甲队率先到达终点 B. 甲队比乙队多走了200米路程 C. 乙队比甲队少用0.2分钟 D. 比赛中两队从出发到2.2分钟时间段，乙队的速度比甲队的速度快 9.班上数学兴趣小组的同学在元旦时，互赠新年贺卡，每两个同学都相互赠送一张，小明统计出全组共互送了90张贺年卡，那么数学兴趣小组的人数是多少？设数学兴趣小组人数为x 人，则可列方程为( ) A. x(x －1)＝90 B. x(x －1)＝2×90 C. x(x －1)＝90÷2 D. x(x ＋1)＝90 10.抛物线2321y x x =-+-的图象与坐标轴交点的个数是（ ） A . 没有交点 B. 只有一个交点 C. 有且只有两个交点 D. 有且只有三个交点 11.在同一坐标系中，一次函数y=ax+2与二次函数y=x 2+a 的图象可能是（ ） A. B. C. D. 12.已知二次函数y=ax 2+bx+c(a ≠0)的图象如图所示，对称轴为x= ﹣12 ．下列结论中，正确的是( ) A. abc ＞0 B. a+b=0 C. 2b+c ＞0 D. 4a+c ＜2b 二、填空题 13.有10个数据的平均数为12，另有20个数据的平均数为15，那么所有这30个数据的平均数是________． 14.将抛物线2y x =先向左平移2个单位，再向下平移3个单位，所得抛物线的解析式为______．
人教版英语八年级下册综合填空专练10篇（附答案） （一） Do you know something about the moon? You can _____ (seeing) it at night. Sometimes it looks round and _____ (brightly). It also looks quite near. _____ the moon is very far from the earth. If you take _____ spaceship, you will get there in more than three days. The spaceship _____ (go) very fast, at 11 kilometers a second. In 1969 two _____ (American) got on the moon by spaceship. There are no living things on the moon _____ there is no air or water there. That's why people can't _____ (liveness) there. But you may know you can jump much higher there than _____ the earth. It's fun, isn't it? I hope some day we Chinese _____ (get) to the moon, too. 答案：see bright but a goes Americans because live on will get （二） Children today have many things to play with. They can watch television, surf ______ Internet, or play video games. But what do you think children _____ (do) for fun long ago? They read books. Some of you might ask, "Are books _____ (real) fun?” Believe it or not, books provide many things that television or computers cannot. Since books use only words _____ (tell) a story, they can improve your imagination. You can picture the characters and background in your head and you can also imagine _____ the characters feel. The words and sentences that are used in storytelling are also very interesting and usually cannot _____ (find) often on television or on websites. They are sometimes so beautiful and touching ______ they can bring tears to your eyes. Books also help us to think harder and _____ (deep). As we continue to read, we ask _____ (our) questions and try to find answers. These are some of the _____ (reason) why books are so fun to read. Remember: the more you read, the more you grow. 答案：the did really to tell how be found that deeper ourselves reasons
习题八 8-1 电量都是q 的三个点电荷，分别放在正三角形的三个顶点．试问：(1)在这三角形的中心放一个什么样的电荷，就可以使这四个电荷都达到平衡(即每个电荷受其他三个电荷的库仑力之和都为零)?(2)这种平衡与三角形的边长有无关系 ? 解: 如题8-1图示 (1) 以A 处点电荷为研究对象，由力平衡知：q '为负电荷 2 220)3 3(π4130cos π412a q q a q '=?εε 解得 q q 3 3- =' (2)与三角形边长无关． 题8-1图 题8-2图 8-2 两小球的质量都是m ，都用长为l 的细绳挂在同一点，它们带有相同电量，静止时两线夹角为2θ ,如题8-2 图所示．设小球的半径和线的质量都可 解: 如题8-2图示 ?? ? ?? ===220)sin 2(π41 sin cos θεθθl q F T mg T e 解得 θπεθtan 4sin 20mg l q = 8-3 根据点电荷场强公式2 04r q E πε= ，当被考察的场点距源点电荷很近(r →0)时，则场强→∞，这是没有物理意义的，对此应如何理解 ?
解: 02 0π4r r q E ε= 仅对点电荷成立，当0→r 时，带电体不能再视为点电 荷，再用上式求场强是错误的，实际带电体有一定形状大小，考虑电荷在带电体上的分布求出的场强不会是无限大． 8-4 在真空中有A ，B 两平行板，相对距离为d ，板面积为S ，其带电量分别为+q 和-q ．则这两板之间有相互作用力f ，有人说f = 2 024d q πε,又有人 说，因为f =qE ,S q E 0ε=，所以f =S q 02 ε．试问这两种说法对吗?为什么? f 到底应等于多少 ? 解: 题中的两种说法均不对．第一种说法中把两带电板视为点电荷是不对的，第二种说法把合场强S q E 0ε= 看成是一个带电板在另一带电板处的场强也是不对的．正确解答应为一个板的电场为S q E 02ε= ，另一板受它的作用 力S q S q q f 02 022εε= =，这是两板间相互作用的电场力． 8-5 一电偶极子的电矩为l q p =，场点到偶极子中心O 点的距离为r ,矢量r 与l 的夹角为θ,(见题8-5图)，且l r >>．试证P 点的场强E 在r 方向上的分量r E 和垂直于r 的分量θE 分别为 r E = 302cos r p πεθ, θ E =3 04sin r p πεθ 证: 如题8-5所示，将p 分解为与r 平行的分量θsin p 和垂直于r 的分量 θsin p ． ∵ l r >>
八年级数学单元试题（时间 120分钟） 一、选择题 1、方程(x-1)(x+2)=0的根是（ ） A 、x 1=1 x 2=-2 B 、x 1=-1 x 2=2 C 、x 1=-1 x 2=-2 D 、x 1=1 x 2=2 2、下列两个三角形中，一定全等的是（ ） A 、有一个角是40°，腰相等的两个等腰三角形 B 、两个等边三角形 C 、有一个角是100°，底相等的两个等腰三角形 D 、有一条边相等，有一个内角相等的两个等腰三角形 3、方程x 2－x ＋2＝0根的情况是（ ） A. 只有一个实数根 B. 有两个相等的实数根 C. 有两个不相等的实数根 D. 没有实数根 4、方程x 2+6x-5=0的左边配成完全平方后所得方程为（ ） A 、(x+3) 2=14 B 、 (x-3) 2=14 C 、(x+6) 2=1 2 D 、 以上答案都不对 5、如图，D 在AB 上，E 在AC 上，且AB ＝AC ，那么 补充下列一个条件后，仍无法判定△ABE ≌△ACD 的条 件是（ ） A 、 AD ＝AE B 、 ∠AEB ＝∠AD C C 、 BE ＝CD D 、 BD=CE 6、如图，△ABC 中，AB=BD=AC ，AD=CD ，则∠BAC 的度数是（ ） A 、100° B 、108° C 、120° D 、150° 7、在联欢晚会上，有A 、B 、C 三名同学站在一个三角形的三个顶点位置上，他们在玩抢凳子游戏，要求在他们中间放一个木凳，谁先抢到凳子谁获胜，为使游戏公平，则凳子应放的最适当的位置在△ABC 的（ ） A 、三边中线的交点 B 、三条角平分线的交点 C 、三边上高的交点 D 、三边垂直平分线的交点 8、如果关于x 的一元二次方程x 2+px+q=0的两根分别为x 1=3， x 2=1，那么这个一元二 次方程是（ ） A 、 x 2+4x+3=0 B 、 x 2-4x+3=0 C 、 x 2+4x-3=0 D 、 x 2-4x-3=0 9、如图所示的图形中，所有的四边形都是正方形， 所有的三角形都是直角三角形，其中最大的正方形 的边长为7cm ，则阴影部分正方形A 、B 、C 、D 的 面积的和是（ ）2 cm 。 A 、28 B 、49 C 、98 D 、147 10、 关于x 的方程2x 2＋mx －1＝0的两根互为相反数，则m 的值为( ) A 、 0 B 、 2 C 、 1 D 、 －2 11、角平分线的尺规作图，其根据是构造两个全等三角形，由作图可知：判断所构造的两个三角形全等的依据是（ ） A 、 HL B 、ASA C 、 SAS D 、 SSS 12、若关于x 的一元二次方程kx 2-6x+9=0有两个不相等的实数根，则k 的取值范围（ ） A 、 k ＜1 B 、 k ≠0 C 、 k ＜1且k ≠0 D 、 k ＞1 二、填空题 13、直角三角形三边是3，4，x ，那么x = 14、关于x 的二次三项式4x 2+mx+1是完全平方式，则m = 15、三角形两边的长分别是8cm 和6cm ，第三边的长是方程x 2－12x ＋20＝0的一个实数根，则三角形的面积是 。 16、方程（m+1）x |m|+(m-3)x-1=0是关于x 的一元二次方程，则m= 17、关于x 的一元二次方程2230kx x -+=有实根，则k 得取值范围是 18、如图，在Rt △ABC 中，∠B=90°，∠A=40°， AC 的垂直平分线MN 与AB 相交于D 点，则 B C
综合填空专项练习 （一） You are so 1. _______ (疲倦的) at night, but you can't sleep. Here are some good ideas. First, you 2. s______ be in a quiet room. That’s important. You should put your feet in some warm water before you go to bed, and that's a 3. ________ / t r ?‘d i ?n ? l / way. You should have a glass of milk. It’s good for sleeping. You should think you are in a 4. ________ / ‘b j u: t i f l/beautiful place. It’s very quiet here, and there are many trees and you walk 5. ______ (slow). That 6. ______ like a good idea. It can help you sleep soon. Sleeping is important to our 7.______ (健康). Don’t be 8. ______ (worry). Go to bed early, eat more vegetables and do some 9. ________. And 10. e_______ will have a good sleep at night. 1. _________ 2. _________ 3. _________ 4. _________ 5. _________ 6. _________ 7. _________ 8. _________ 9. _________ 10. _________ （二） Amanda is a very kind girl. She is always 11. ______ (will) to help people who are in 12. ________. Now Amanda is 13. s____ in the university of Texas. At the same time, she is volunteering to teach at Heart House in her 14____ time. Heart House is a local after－school program for children. It 15____ /p r?‘v ai d z/ some extra education for those children who are not doing well in their studies. Amanda goes to Heart House to teach the children twice a week. She has also 16____ (make) a website for Heart House. In this way, more people have more chances to learn about Heart House and help the children there. Because of Amanda's website, every week 125 volunteers 17____ (花费) about four hours helping the children at Heart House now.“Without Amanda's website, Heart House would be 18. u____ to have enough volunteers. Her support is much appreciated,”the program leader says. “I feel happy to teach those kids how to study. The 19. ____ /‘h?p i s t/ thing is that I can also learn a lot from them. I won't give up volunteering after graduation. I hope to 20____ (继续)teaching kids who need help,” Amanda says. 11. _________ 12. _________ 13. _________ 14. _________ 15. _________ 16. _________ 17. _________ 18. _________ 19. _________ 20. _________ (三) I work in a cleaning company. Usually people call us, and we provide house cleaning 21. _________ /’s?:rvis/. One day, I got a call from a man named David. “I want to help an old man. He just had surgery (手术)and is still 22. i____. Can I pay for it without letting him know？”he asked. David
D A B C 八年级下册数学期末测试题一 一、选择题（每题2分，共24分） 1、下列各式中，分式的个数有（ ） 31-x 、12+a b 、πy x +2、21--m 、a +21、2 2) ()(y x y x +-、x 12-、115- A 、2个 B 、3个 C 、4个 D 、5个 2、如果把 223y x y -中的x 和y 都扩大5倍，那么分式的值（ ） A 、扩大5倍 B 、不变 C 、缩小5倍 D 、扩大4倍 3、已知正比例函数y =k 1x (k 1≠0)与反比例函数y =2 k x (k 2≠0)的图象有一个交点的坐标为(－2，－1)，则它的另一个交点的坐标是 A. (2，1) B. (－2，－1) C. (－2，1) D. (2，－1) 4、一棵大树在一次强台风中于离地面5米处折断倒下，倒下部分与地面成30°夹角，这棵大树在折断前的高度为 A ．10米 B ．15米 C ．25米 D ．30米 5、一组对边平行，并且对角线互相垂直且相等的四边形是（ ） A 、菱形或矩形 B 、正方形或等腰梯形 C 、矩形或等腰梯形 D 、菱形或直角梯形 6、把分式方程12121=----x x x 的两边同时乘以(x －2), 约去分母，得( ) A ．1－(1－x)=1 B ．1+(1－x)=1 C ．1－(1－x)=x －2 D ．1+(1－x)=x －2 7、如图，正方形网格中的△ABC ，若小方格边长为1，则△ABC 是（ ） A 、直角三角形 B 、锐角三角形 C 、钝角三角形 D 、 以上答案都不对 （第7题） （第8题） （第9题） A B C
综合填空一 根据首字母提示补全单词，完成短文。 One day when Tony was crossing the road. A car hit him. He fell down and b 1 his arm. An ambulance(救护车) soon arrived and t 2 him to a hospital. A doctor put the arm in a plaster cast(上石膏). Tony could not move it at all. “You m ust k 3 your arm in the cast for six weeks.” the doctor said, “That would give the broken arm a c 4 to heal(痊愈).” Six weeks later, Tony went back to the h 5 . The doctor cut the cast w 6 a large saw(锯) and took the arm out of the cast. “Can you move your arm, Tony?” He asked. Tony tried to m7 his arm. At first it was difficult, but soon he was able to move it a little. “Yes, it’s fine,” He said, “Thanks, doctor.” “It will b8 as good as usual(像以往一样) soon.” The doctor said, “Just e9 it a little.” “Will I be able to play the piano?” Tony asked. “Of c10 you will,” He said. “That is a good news,” Tony said, “I couldn’t play it at all before.” Keys: 1. broke 2. took 3. keep 4. chance 5. hospital 6. with 7. move 8. be 9. exercise 10. course 综合填空二 用适当的词完成句子，使短文意思完整。 There are 47 different kinds of Kangaroos(袋鼠). The smallest are about a quarter of a meter long. The 1 are taller than a man. Kangaroos have very long strong back 2 . These are used for 3 . They also have 4 strong tails for resting on. Kangaroos’ front legs are 5 shorter, and are almost like arms. Kangaroos’ heads are quite small, but their ears are quite large. Keys: 1. biggest 2. legs 3. jumping 4. long 5. much 综合填空三 I went to have a dinner party at the biggest hotel in my hometown today. I was very busy, 1 I had no time to change 2 for dinner. Then I drove there as soon as I could 3 when I walked in, no one 4 me to food or drink.
习题9 9.1选择题 (1)正方形的两对角线处各放置电荷Q，另两对角线各放置电荷q，若Q所受到合力为零， 则Q与q的关系为：（） （A）Q=-23/2q (B) Q=23/2q (C) Q=-2q (D) Q=2q [答案：A] (2)下面说法正确的是：（） （A）若高斯面上的电场强度处处为零，则该面内必定没有净电荷； （B）若高斯面内没有电荷，则该面上的电场强度必定处处为零； （C）若高斯面上的电场强度处处不为零，则该面内必定有电荷； （D）若高斯面内有电荷，则该面上的电场强度必定处处不为零。 [答案：A] (3)一半径为R的导体球表面的面点荷密度为σ，则在距球面R处的电场强度（） （A）σ/ε0 （B）σ/2ε0 （C）σ/4ε0 （D）σ/8ε0 [答案：C] (4)在电场中的导体内部的（） （A）电场和电势均为零；（B）电场不为零，电势均为零； （C）电势和表面电势相等；（D）电势低于表面电势。 [答案：C] 9.2填空题 (1)在静电场中，电势梯度不变的区域，电场强度必定为。 [答案：零] (2)一个点电荷q放在立方体中心，则穿过某一表面的电通量为，若将点电荷由中 心向外移动至无限远，则总通量将。 [答案：q/6ε0, 将为零] (3)电介质在电容器中作用（a）——（b）——。 [答案：(a)提高电容器的容量;(b) 延长电容器的使用寿命] (4)电量Q均匀分布在半径为R的球体内，则球内球外的静电能之比。 [答案：1：5] 9.3 电量都是q的三个点电荷，分别放在正三角形的三个顶点．试问：(1)在这三角形的中心放一个什么样的电荷，就可以使这四个电荷都达到平衡(即每个电荷受其他三个电荷的库仑力之和都为零)?(2)这种平衡与三角形的边长有无关系? 解: 如题9.3图示 (1) 以A处点电荷为研究对象，由力平衡知：q 为负电荷
2014年八年级数学（下） 期末调研检测试卷（含答案） 一、选择题（本题共10小题，满分共30分） 1 ．二次根式 2 1、12 、30 、x+2 、240x 、22y x +中，最简二次根 式有（ ）个。 A 、1 个 B 、2 个 C 、3 个 D 、4个 2.若式子2x -有意义，则x 的取值范围为（ ）. A 、x≥2 B 、x≠3 C 、x≥2或x≠3 D 、x≥2且x≠3 3．如果下列各组数是三角形的三边，那么不能组成直角三角形的一组数是（ ） A ．7，24，25 B ．1113,4,5222 C ．3，4， 5 D ． 114,7,8 22 4、在四边形ABCD 中，O 是对角线的交点，能判定这个四边形是正方形的是（ ） （A ）AC=BD ，AB ∥CD ，AB=CD （B ）AD ∥BC ，∠A=∠C （C ）AO=BO=CO=DO ，AC ⊥BD （D ）AO=CO ，BO=DO ，AB=BC 5、如图，在平行四边形ABCD 中，∠B ＝80°，AE 平分∠BAD 交BC 于点E ，CF ∥AE 交 AE 于点F ，则∠1＝（ ） 1 F E D C B A A ．40° B ．50° C ．60° D ．80° 6、表示一次函数y ＝mx +n 与正比例函数y ＝mnx (m 、n 是常数且mn ≠0)图象是（ ） 7.如图所示，函数 和3 4 312+= x y 的图象相交于（－1，1），（2，2）两点．当21y y >时，x 的取值范围是（ ）
A ．x ＜－1 B ．—1＜x ＜2 C ．x ＞2 D ． x ＜－1或x ＞2 8、 在方差公式( )()( )[]2 22212 1 x x x x x x n S n -++-+-=Λ中，下列说法不正确的是 （ ） A. n 是样本的容量 B. n x 是样本个体 C. x 是样本平均数 D. S 是样本方差 9、多多班长统计去年1～8月“书香校园”活动中全班同学的课外阅读数量（单位：本），绘制了如图折线统计图，下列说法正确的是（ ） （A ）极差是47 （B ）众数是42 （C ）中位数是58 （D ）每月阅读数量超过40的有4个月 10、如图，在△ABC 中，AB =3，AC =4，BC =5，P 为边BC 上一动点，PE ⊥AB 于E ，PF ⊥AC 于F ，M 为EF 中点，则AM 的最小值为【 】 A ．54 B ．52 C ．53 D ．65 二、填空题（本题共10小题，满分共30分） 11．48 -1 -?? +)13(3--30 -23-= M P F E C B A