助滤剂可改善过滤效果。
参考答案:对
People usually think tigers are scary.[ ]
A. kind
B. kinds of
C. a kind of
D. kind of
下列哪种试验线圈系统检测管材的小缺陷最好?()
A.围绕线圈;
B.内部探头线圈;
C.表面探头线圈;
D.A和B