【单选题】She was _______ tired that she fell asleep immediately. [ ]
【单选题】As she _____ the newspaper, Granny _____ asleep.
D.
was reading; was falling
【单选题】硅稳压二极管的稳压功能是利用 ( ) 来实现的
【单选题】She ______ for ten hours at least. It was at nine that she fell asleep last night.
【简答题】PLC梯形图语言中,画出常开触点、常闭触点和线圈的符号