问题 选择题
回旋加速器是加速带电粒子的装置,其核心部分是分别与高频交流电两极相连接的两个D形金属盒,两盒间的狭缝中形成周期性变化的匀强电场,使粒子在通过狭缝时都能得到加速,两D形金属盒处于垂直于盒底面的匀强磁场中,如图所示,设匀强磁场的磁感应强度为B,D形金属盒的半径为R,狭缝间的距离为d。匀强电场间的加速电压为U,要增大带电粒子(电荷量为q、质量为m,不计重力)射出时的动能,则下列方法中正确的是(   ) 

A.增大匀强电场间的加速电压

B.减小狭缝间的距离

C.减小磁场的磁感应强度

D.增大D形金属盒的半径

答案

答案:D

完形填空

Are only clever and good-looking students happy in the school? Best-selling ___31___ Xiao Nizi (Nini) doesn’t think so.

___32___ has his own place in the sky." she said.  "We're all special in our ownways.”

Nini, from Hunan, writes stories about young people in the school. Her books,___33___ Devils Kiss and Un-e on Midsummer’s Night, are very ___34___ with students.

In her stories, the main characters arc usually common girls who are neither pretty ___35___ smart. But they always win the love of a Prince Charming(白马王子),or___36___ successful stars.

"It’s not because of luck."' said Nini. ""They are ___37___ honest and they don't lie. They know what they arc good___38___ and work hard to realize their dreams. "

Nini herself is like one of the characters in her stories. She was a shy girl at school. But she thought a lot and liked languages, and that made her ___39___ to be a writer. She hopes her stories ___40__ make more kids happy.

小题1:A. writer        B. reader         C. speaker

小题2: A. Nobody     B. Everyone      C. Someone

小题3:A. as           B. for example    C. such as

小题4: A. successful    B. popular        C. funny

小题5: A. nor          B. or            C. but

小题6:A. become      B. make         C. take

小题7: A. still          B.only         C. ever

小题8: A. at           B. for           C. with

小题9:A. deciding      B. to decide      C. decide

小题10: A. can          B. must        C. need

选择题