机电设备运转时（）。
A、不准碰触施转部件
B、不准碰触运转部件
C、可以清扫运转部件
参考答案：C
The number of people invited _____ fifty, but a number of them ____ absent for different reasons.
A．were; was
B．was; was
C．was; were
D．were; were
