地质队员在山谷中用锤子敲打石块，经0.5s听到了第一次回声后，又经过1.5s听到

The teacher asked us to stop         and          him carefully.[ ]

A. reading; listening to  

B. reading; to listen to

C. to read; to listen to    

D. to read; listening to

—Is Paul playing basketball for his school?

—Well,he ____.But he has given it up and switched to playing volleyball.

A．is

B．was

C．has

D．had

客户应用（）填写“西联汇款发汇单”。

A、英文 

B、中文 

C、中文或英文均可以 

D、法文 

蒸发室内吸液芯的作用原理是（）。

A.过滤气体

B.吸收储存麻醉药液

C.毛细虹吸扩大气液表面

D.降低热传导

E.减缓载气流动

反映股票基金风险大小的指标有（）。

A.贝塔值

B.标准差

C.持股集中度

D.持股数量