-- You look so tired.
--- Yes. I _____ the house all the morning. But I’m finishing it soon.
A. have cleaned B. have been cleaning
C. have been cleaned D. had been cleaning
Police in America have stepped up their search for a fifteen-year-old boy who went _____ three days ago.
A. going B. losing
C. missing D. disappearing
There are _____ flights between the two cities, _____ it convenient for people in one city to travel to work in the other.
A. regular; to make B. usual; making
C. usual; having made D. regular, making
Though faced with so many difficulties, they are _____ about their future.
A. curious B. enthusiastic
C. optimistic D. concerned
The Sahara Desert is almost _____ of the US.
A. as big B. the size
C. the area D. the same
We shall never forget the days ________ we spent playing happily together.
A. in which B. which C. when D. on which
