The recent earthquakes have caused concern because they happen _____ population centers and have caused huge damage.
The professor _______ to walk out of the office when one of his students came in.
Look, the little girl is dancing as if she ______ a little bird.
The teacher told me that the earth _______ round.
----Jack hasn’t got a job yet, has he? ---- Oh yes, in fact, he has been ________ for two weeks.
----What do you think of this film? ----Very bad. __________.