微机型防误闭锁装置的主机必须专机专用，严禁（）
A.与英特网互连
B.可以上网
C.可以打印工作票
D.兼做他用
参考答案：A, D
—All the building materials have been washed away.
—So I have heard. But there was no sign ____ a heavy rain was on the way last night.
A．when
B．that
C．which
D．If
瞀儒 mào rú
