With the help of high technology, more and more substances _________ in the past years.
A.discovered | B.have discovered |
C.had been discovered | D.have been discovered |
The professor can answer almost any question __________we have about any history topic.
A.as | B.that | C.why | D.where |
Due to the light pollution, stars are too faint _________with naked eyes in the urban area.
A.observing | B.being observed |
C.to be observed | D.to be observing |
--Why won’t you go to Jim’s birthday party with us?
--Well, I don’t like him, if you ________know.
A.can | B.may | C.must | D.should |
He failed the driving test though he __________for a long time.
A.practises | B.has practised |
C.was practising | D.had been practising |
Hotels fill up fast during the busy tourist season, __________it is necessary for tourists to make reservations in advance.
A.or | B.so | C.for | D.but |