Messages ______ be changed from sound into electricity before they ______ be sent by radio.
A. must; will B. have to; can C. can; must D. need; may
He _____ his parents that he has failed in the exam.
A. dares not tell B. dares not telling C. dare not tell D. dares not to tell
—The poor people lived near the highway.
—_____ very noisy.
A. It must have been B. They must be C. That might be D. There must be
As is natural, a man as old as he ______ be very forgetful.
A. can B. must C. should D. would
You _____ pay too much attention to your reading skill, as it is so important.
A. cannot B. should C. must D. needn’t
I _____ have written to him because he phoned me shortly afterwards.
A. ought to B. must C. couldn’t D. needn’t
