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

A. slowly

B. its

C. blinking

D. and

Câu 2: The chief of police demanded from his assistants an orderly investigation, a well-written report, and that they work hard.

A. The chief

B. from

C. orderly

D. that they work hard

Câu 3: 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 4: Collecting stamps, playing chess and to mount beautiful butterflies are derrick’s hobbies.

A. collecting

B. playing

C. to mount

D. are

Câu 5: When a patient's blood pressure is much higher than it should be, a doctor usually insists that he will not smoke.

A. much

B. than it

C. should be

D. will not

Câu 6: What happened in New York were a reaction from city workers, including firemen and policemen who had been laid off from their jobs.

A. What happened

B. were

C. including

D. their