用括号内所给动词的适当形式填空。

1. Mr Johnson likes _____  (watch) TV in the evening.

2. He_____  (go) fishing yesterday.

3. What _____ you_____ (do) this weekend?

4. Listen! Someone_____ (sing) in the next room.

5. Mrs Beet_____ (drive) very fast to work every day.

当采用需要系数法计算负荷时，短时或周期工作制电动机应统一换算到负载持续率为( )下的功率。

A．90%

B．75%

C．100%

D．25%