Câu hỏi: Some snakes have hollow teeth they are called fans that they use to poison their victims.

A. Some 

B. they are called

C. use

D. their

Câu 1: An endangered species is the one _________ population is so small that it is in danger of becoming extinct.

A. which

B. what

C. whose

D. who

Câu 2: _________, we would have been forced to sack him.

A. Were he not to resign

B. If he resigned

C. Had he not resigned

D. If he had resigned

Câu 3: George is not enough intelligent to pass this economics class without help.

A. enough intelligent

B. to pass

C. economics

D. help

Câu 4: What the woman was saying were so important that I asked everyone to stop talking and listen.

A. What

B. was saying

C. were

D. to stop taking

Câu 5: While Peter ________the rose bush in the back yard, the phone rang.

A. were watering

B. has watered

C. watered

D. was watering

Câu 6: After David _________ his homework, he went straight to bed.

A. had finished

B. has finished

C. was finished

D. finished