Câu hỏi: Exactly .............. we can replace our soil disappearing through erosion is not known.

A. what

B. how

C. if

D. because

Câu 1: Take John's address with you, ................... you have time to see him whenyou’re in London.

A. if

B. unless

C. in case

D. so long as

Câu 2: A small design fault ................. on our latest chip.

A. has found

B. found

C. has been found 

D. find

Câu 3: Their popularity ................ much more after the Second WorldWar.

A. grew

B. grow

C. is grown

D. has grown

Câu 4: Be careful about the time. If you .................. too long on the first question,you ............... enough time to do the others properly.

A. had spent - would not have

B. had spent – would not have had

C. spend - will not have

D. spent - would not have had

Câu 5: Send my regards to Lawrence ............................ you see him.

A. if

B. in case

C. whether

D. provided

Câu 6: Peasants spend most of their time on the ground, ...................... many speciesstay in trees at night.

A. if

B. though

C. because

D. as well as