如图13-1-9所示，水面上漂浮着一半径为r的圆形薄木板，在木板圆心的正上方距木

发布时间：2017-07-26 03:08 │ 来源：www.tikuol.com

题型：问答题

问题：

如图13-1-9所示，水面上漂浮着一半径为r的圆形薄木板，在木板圆心的正上方距木板高度h的A处有一个点光源S.由于木板的影响，点光源发出的光线射入水中后，在水底平面上形成一圆形阴影.已知水深为H，水的折射率为n，求阴影的半径.

图13-1-9

考点：光的折射定律

题型：问答题

完形填空。
Richard found work in a big office after he had finished college. He liked to use his (1)____and was good (2)_____ his work. So he was often paid more than his workmates and he worked (3)______. But something was wrong with the young man one month. He couldn't fall (4)____ at night. So he was always (5)_____ in the daytime and often made mistakes. He had to go to a hospital.The (6)______ looked him over and (7)_____ him to buy some highly effective sleeping pills(高效安眠药). He took them (8)_____ the went to bed. Soon after that he went to (9)_____. Richard (10)_____ in the morning, he had a look at the (11)_____ on the wall. It was a quarter to seven. He got up and went to work after (12)____ . As soon as he went in the office, he said to the head of the office, "Good morning, Mr. Clarke! I've(13)_____ had a good sleep like last night's. And I'm feeling (14)_____better now!" "Skunk(混蛋)!" the head (15)_____ loudly.”We've looked for you for two days! I wanted you to do something important, but it's too late now!"
( )1. A. hand ( )2 A. for ( )3. A. hard ( )4. A. asleep ( )5. A. well ( )6. A. doctor ( )7. A. tell ( )8. A. after ( )9. A. asleep ( )0. A. stood up ( )11. A. o’clock ( )12. A. meal ( )13. A. always ( )14. A. much ( )15. A. laughed	B. head B. in B. fast B. alone B. hungry B. policeman B. say B. since B. sleeping B. woke up B. map B. dinner B. usually B. more B. shouted	C. ear C. with C. harder C. afraid C. thirsty C. driver C. ask C. before C. sleep C. at down C. picture C. party C. never C. most C. smiled	D. nose D. at D. faster D. behind D. tired D. nurse D. told D. because D. slept D. lay down D. clock D. breakfast D. often D. than D. asked

查看答案

题型：问答题

如图所示，电阻值为R的导线接在a、b两端，电压表的读数为12V，电流表的读数是0.8A，若换用电阻值为4R的导线接在a、b两端，则电压表和电流表的读数分别为

A．3V、0.2 A

B．12V、0.2 A

C．3V、0.8 A

D．12V、3.2 A

查看答案

题型：问答题

治疗卵巢肿瘤的主要方法是（）

A.孕激素治疗

B.化疗

C.放疗

D.手术治疗

E.综合治疗

查看答案

题型：问答题

浏阳市哪个合作社获得“全国农机示范合作社”称号？

查看答案

题型：问答题

下列图标表示（）

A.电流互感器

B.发电厂

C.双三角连接

查看答案

更多题库