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: Conservation is the safeguarding and preservation of nature resources.

A. is

B. safeguarding

C. preservation

D. nature

Câu 2: Do most boys and girls give a great deal of thought to their future employ?

A. most

B. give

C. thought

D. employ

Câu 3: 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

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

A. tell

B. when

C. left

D. saying

Câu 5: The deadbolt is the best lock for entry doors because it is not only inexpensive but installation is easy.

A. the best

B. because

C. not only

D. installation is easy

Câu 6: 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