Câu hỏi: I clearly remember to tell you about this before.

A. clearly

B. remember

C. to tell 

D. about

Câu 1: Sometimes it takes me about three hours finishing my round.

A. sometimes

B. me

C. hours

D. finishing

Câu 2: John announced that he could not longer tolerate the conditions of the contract under which he was working.

A. announced that

B. not longer tolerate

C. of

D. under which

Câu 3: Manufacturers may use food additives for preserving, to color, or to flavor, or to fortify foods.

A. may use

B. for preserving

C. to flavor

D. to fortify

Câu 4: An ambitious person is committed to improve his or her status at work.

A. is

B. improve

C. status

D. at

Câu 5: Passengers are required to arrive to the gate fifteen minutes before departure time.

A. are required

B. to arrive to

C. before

D. departure time

Câu 6: By measuring the color of a star, astronomers can tell how hot is it.

A. measuring

B. the

C. how

D. is it