We must do whatever we can to ______the river from being polluted any more.
| A．separate | B．keep | C．prevent | D．guard |
Our new house is very___________ for me as I can get to the office in five minutes
| A．convenient | B．comfortable | C．natural | D．helpful |
--I can't find Mr. Smith.
--It was in the hotel___________ he stayed.
| A．that | B．where | C．which | D．since |
Scientists say it may be five or ten years___________ it is possible to test this medicine on human patients.
| A．since | B．before | C．after | D．when |
My uncle___________ until he was forty-five.
| A．married | B．didn’t marry |
| C．was not marrying | D．would marry |
--What ____________when I phoned you?
----I_____________and began to have a bath.
| A．had you done; finished | B．were you doing; had just finished |
| C．did you do; had just finished | D．were you doing; was finishing |