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 master of ceremonies announced in a loud and clear voice and told that the dinner would be late due to unforseen circumstances.

A. of ceremonies

B. and told

C. would be

D. due to

Câu 2: Slowly and with care, the museum director removed the Ming vase from the shelf and placed it on the display pedestal.

A. with care

B. from

C. placed

D. the display pedestal

Câu 3: 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 4: The puppy stood up slowly, wagged its tail, blinking its eyes, and barked.

A. slowly

B. its

C. blinking

D. and

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: Narcissus, a character in mythology, gazed at his own image in a pool so ardently that he fell into itself and downed.

A. a character in mythology

B. his own

C. that

D. into itself