你知道下列短语的意思吗？选选看！

(     )1. as weak as a cat

(     )2. lucky dog

(     )3. monkey see, monkey do

(     )4. as timid as a rabbit

A. 幸运儿    

B. 有样学样

C. 胆小如鼠    

D. 身体非常虚弱的

用于观察运动单位电位发放率时的示波器扫描速度为（）

A.5ms/cm

B.20～50ms/cm

C.10ms/cm

D.100ms/cm

E.1000ms/cm