I want to know what _____. [ ]
A. wrong is
B. is wrong
C. the matter
D. is matter
答案:B
He is late _____the meeting yesterday. [ ]
A. in
B. on
C. for
D. of
金属屋面或钢筋混凝土屋面内的钢筋进行接地,有良好的()和一定的屏蔽作用。