— pen is lost. May I use yours?
—Certainly. Here you are. [ ]
A. I
B. Me
C. My
D. Mine
答案:C
汽压波动对锅炉水位的影响是怎样的?
压阀属于()。
A.关断阀;
B.调节阀;
C.安全阀;
D.疏水阀。