潜油泵叶轮的级数很多，可达到几百级。
参考答案：对
There are some seemingly insignificant matters that, when _______ in time, can become bigger ones later on.
A．not dealt with
B．not being dealt with
C．not to be dealt with
D．not having been dealt with
用起重机装卸爆破器材时，一次起吊质量不应超过设备能力的（）。
A.30%
B.40%
C.50%
