2.(　 )甲、乙、丙三辆汽车以相同的速度同时通过某一路标，从此时开始甲车一直做匀速直线运动，乙车先加速后减速，丙车先减速后加速，它们经过下一个路标的速度又相同。则最先通过下一路标的应是　

　　 A．甲　　 　B．乙　　 　C.丙　 　　D．条件不足，无法判断

1.(　 )图示为高速摄影机拍摄到的子弹穿过苹果瞬间的照片。该照片经过放大后分析出，在曝光时间内，子弹影响前后错开的距离约为子弹长度的1%~2%。已知子弹飞行速度约为500m/s，因此可估算出这幅照片的曝光时间最接近

A、10^-3s　 　B、10^-6s　 C、10^-9s　　 D、10^-12s

19.(★★★★★)-Who gave you this message?

　　 -A man________himself Mr.Zhang.

　　 A.called B.calling C.calls D.is called

18.(★★★★★)-Would you mind________me the dicionary?

　　 -Of couse not.But it is ________my reach.

　　 A.passing;out B.passing;beyond

　　 C.to pass;far away D.to pass;out of

17.(★★★★★)Silver is the best conductor of electricity,copper________it closely.

　　 A.followed B.to follow C.following D.being followed

16.(★★★★)With his son________,the old man felt unhappy.

　　 A.to disappoint B.to be disappointed

　　 C.disappointing D.being disappointed

15.(★★★★)________good,the food was soon sold out.

　　 A.Tasted B.Being tasted

　　 C.Tasting D.Having tasted

14.(★★★★)O’Neal works hard.He is often seen________heavily before his teammates have even arrived at practice.

　　 A.sweated B.to be sweated

　　 C.sweating D.being sweated

13.(★★★★)He didn’t seem to mind________TV while he was trying to study.

　　 A.he easily watches B.his easy watching

　　 C.his easily watching D.hiseasilywatched.

12.(★★★★)The time he has devoted in the past ten years________the disabled is now considered ________of great value.

　　 A.to help;being B.to helping;to be

　　 C.help;to be D.helping;being