起重机的驱动方式分为两类:()。
参考答案:集中驱动与分别驱动
-Does he play sports?
-No, __________. He only watches them ________TV. [ ]
A. he does, on
B. he doesn't, in
C. he doesn't,on
熔断器内的熔体,在电路里所起的作用是()
A、过载保护
B、失压保护
C、短路保护
D、低频保护