Câu hỏi: We ....................... in the plane for hours when it finally, took off.

A. had been sitting

B. have sat

C. will be sitting

D. will sit

Câu 1: The new project received a lot of financial assistance from the WTO; ..............., it could easilybe approved by the authority.

A. thus

B. on the other hand

C. on the contrary

D. inaddition

Câu 2: The old drainage pipelines must be maintained; ................, leakage will be unavoidable.

A. therefore

B. similarly 

C. on the contrary

D. otherwise

Câu 3: My parents    ........... in Florida since 1999.

A. has lived

B. have lived

C. are living

D. live

Câu 4: I .............. Michael for years.

A. have known

B. know

C. knowing

D. was known

Câu 5: We .............. since 5:00.

A. talk

B. are talking

C. talking

D. have been talking

Câu 6: I ................. the house before you called.

A. leave

B. am leaving

C. had left

D. had been leaving