JK提升机空负荷运转时,盘形闸与闸盘的接触面积必须大于()。
A、10%
B、30%
C、60%
D、90%
参考答案:C
The hotline_________ be very busy,but keep trying and you’ll get through.
A.should
B.must
C.can
D.would
性格