Câu hỏi: 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 1: Before went abroad, he had finished his English course at the English-speaking Center.

A. went

B. abroad

C. had finished

D. English-speaking

Câu 2: The puppy stood up slowly, wagged its tail, blinking its eyes, and barked.

A. slowly

B. its

C. blinking

D. and

Câu 3: 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 4: Please tell us the reason when he left without saying goodbye.

A. tell

B. when

C. left

D. saying

Câu 5: In spite of my father is old , he gets up early and does morning exercise.

A. In spite of

B. is

C. gets up

D. does morning exercise

Câu 6: Despite America’s affluence, many people are without jobs, on welfare, and have a lot of debts.

A. Despite

B. without jobs

C. on welfare

D. have a lot of debts