Câu hỏi: Proteins are made up of folded irregularly chains, the links of which are amino acids.

A. made up of

B. folded irregularly

C. the links

D. which

Câu 1: My father asked me where had I gone the night before.

A. the

B. asked me

C. had I

D. before

Câu 2: The number of students attending universities to study economics have increased steadily in the last few years.

A. of students

B. attending

C. economics

D. have

Câu 3: A smile can be observed, described, and reliably identify, it can also be elicited and manipulated under experimental conditions.

A. identify

B. experimental

C. can also

D. A smile

Câu 4: Henry David Thoreau was an American writer who is remembered for his faith in religious significance of the nature.

A. an

B. is

C. for

D. the nature

Câu 5: Tom said that he was trying to carry out some campaigns to protect environment and will encourage others to do so.

A. he was trying

B. some

C. campaigns

D. will

Câu 6: It is very difficult for her to prevent him for smoking in her house.

A. very

B. for 

C. prevent 

D. for smoking