Câu hỏi: Unless there had been a heavy storm, the climbers will not have died.

A. Unless

B. had been

C. heavy

D. will

Câu 1: Jason’s professor had him to rewrite his thesis many times before allowing him to hand it in.

A. had

B. to rewrite

C. many times

D. allowing

Câu 2: She wishes that we didn’t send her the candy yesterday because she’s on a diet.

A. didn’t send

B. her the candy

C. because

D. on

Câu 3: Spell correctly is easy with the aid of a number of word processing programs for personal computers.

A. Spell

B. correctly

C. word processing

D. computers

Câu 4: Ecologists are trying to preserve our environment for future generations by protecting the ozone layer, purifying the air, and have planted the trees that have been cut down.

A. to preserve

B. for

C. the ozone layer

D. have planted

Câu 5: This apprentice has spent two weeks to work on that new machine.

A. has spent

B. to work

C. on

D. new machine

Câu 6: Collecting stamps, playing chess and to mount beautiful butterflies are derrick’s hobbies.

A. collecting

B. playing

C. to mount

D. are