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

A. tell

B. when

C. left

D. saying

Câu 2: Today's job seekers are confronted with such question as "Are you computer literate?" and "Can you set up a data base?"

A. job

B. confronted

C. such question

D. set up

Câu 3: 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 4: Do most boys and girls give a great deal of thought to their future employ?

A. most

B. give

C. thought

D. employ

Câu 5: 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 6: Abraham Lincoln was a good president and was self-educated, hard working and always told the truth.

A. a good president

B. self-educated

C. hard working

D. always told the truth