Câu hỏi: We need to protect ....... environment from pollution.

A. some

B. a

C. an

D. the

Câu 1: The children have ........ new teacher called Mr. Green.

A. a

B. an

C. the

D. x

Câu 2: ......... European expert was invited to speak to the committee.

A. a

B. an

C. the

D. x

Câu 3: Alex is in Boston studying for .... MBA.

A. a

B. an

C. the

D. x

Câu 4: The Mississippi river is in ........ United States of America.

A. a

B. an

C. the

D. x

Câu 5: Danny wanted ........... new bicycle for Christmas.

A. a

B. an

C. the

D. x

Câu 6: We often go to school by ........ bicycle.

A. some

B. a

C. an

D. the