过滤时，为了防止较小粒子堵塞过滤介质的滤孔，常常在滤布面上预涂一层被称作助滤剂的涂料。
参考答案：对
The girl spent as much time as she ____ her lessons.
A．could going over
B．could go over
C．went them over
D．went over
如果电网容量允许，笼型异步机电动机应采用（）。
A、直接起动
B、Y—△起动
C、Y—Y起动
D、软起动
