It was essential that the application forms ___________ back before the deadline .
A. must be sent B. would be sent
C. be sent D. were sent
_____________ cease（终止） advertising, prices would be significantly reduced.
A. Were they to B. Could they
C. If they D. Would they
Much labor would have been saved if the electronic computers_____________ before.
A. had invented B. were invented
C. should have been invented D. had been invented
There was a(n)________silence in the live interview，when no one knew what to say to the audience.
A．ashamed B．disappointed C．desperate D．awkward
Doctors are doing research to find out what happens physically when people______ smoking.
A．quit B．decline C．prevent D．reserve
Once you get _______ something, it is very hard to ________.
A. addicted to; rid yourself of it
B. used to; rid yourself of it
C. accustomed to; be got rid of it
D. addicted to; get away with it
