信号报警与联锁保护装置的触点式，可用继电器或（）
A.开关
B.接触器
C.晶体管
D.电磁阀
参考答案：B
—Could you please lead your car to me this Sunday?
—_________you have it cleaned after using it.
A．Although
B．So long as
C．Even if
D．As soon as
可控制硅从导通转化为关断必须具备哪些条件？
