Câu hỏi: 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 1: Not everyone realizes that the most largest organ of the human body is the skin.

A. not everyone

B. most largest

C. human

D. is

Câu 2: Little have people done to alleviate the sea pollution caused by the factories in central Vietnam, haven’t they?

A. have people done

B. caused

C. in central

D. haven’t they

Câu 3: Generally, Europe and Asia are regarded as being distinct continents, but they are simply vast geography divisions of the larger lad mass known as Eurasia.

A. Generally

B. are regarded

C. vast geography

D. known as

Câu 4: 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 5: I clearly remember to tell you about this before.

A. clearly

B. remember

C. to tell 

D. about

Câu 6: For thousands of years, man has created sweet-smelling substances from wood, herbs and flowers and using them for perfumes or medicine.

A. man

B. sweet-smelling

C. using them

D. or