While _______ out of the window, I saw my father walking the dog in the garden.
A. look B. looking
C. looked D. having looked
Our monitor always comes to our help when we get into trouble _______ she is very busy.
A. since B. once
C. even if D. if
Can you tell me when the plane _______ to Hong Kong this evening?
A. would fly B. has flown
C. is flying D. had flown
As neither of the two nations would _______, no agreement was reached that day.
A. give up B. give away
C. give back D. give in
It was because of your attitude to your parents _______ they felt so upset.
A. what B. that C. who D. so that
Every year _______ foreign visitors come to Beijing to pay a visit to the places of interest.
A. tens of thousands of B. ten thousands of
C. ten thousands D. thousands upon thousands
