TCU主要功能。()
A.触发
B.监测晶闸管
C.保护触发
D.恢复期保护
参考答案:A, B, C, D
—What does he do?
—________. [ ]
A. He is very well
B. He is eleven
C. He is in a hospital
D. He is a worker
在问卷的基本结构中,()要求简短明了,有的问卷也可以省略。
A.前言
B.序言
C.结束语
D.引言