15. When Madam Curie did the experiment again, she was more careful where she _____ a mistake.
A.made | B.has made | C.was making | D.had made |
He apologized for ______ to inform me of the change in the plan.
A.his being not able | B.him not to be able |
C.his not being able | D.him to be not able |
more time, we could do it better.
A.Giving | B.Given | C.Give | D.To give |
Helen plays the violin ________, if not better than, Kate.
A.as well | B.so well | C.as well as | D.so well as |
—You seem to have known Dr. Ken for a long time.
—That’s true. ________ he joined our club years ago.
A.Since | B.Until | C.When | D.If |
You _______ her in her office last Friday; she’s been out of town for two weeks.
A.needn’t have seen | B.must have seen | C.shouldn’t have seen | D.can’t have seen |