It's hard to turn down a banana． They taste good and you don't have to wash them __________eating them．（ ）
A．untilB．afterC．before
Are you willing to live on Mars one day？
__________． It sounds interesting， but it still worries me．（ ）
A．I'm not sureB．Sure， I will
C．That's all rightD．I hope so
Could you tell me____ so well？
Without the teacher's help， it was impossible for me to get the prize．（ ）
A．how did you do itB．when you did it
C．why did you do itD．how you did it
It is 4：30 pm． Ben and Leon _______ their work， so they are playing chess now．（ ）
A．finishB．finished
C．have finishedD．will finish
I'm sorry I can't finish the task on time because I ____ only 10 minutes．（ ）
A．will giveB．was givenC．am givenD．gave
I just saw Peter in the library．
It _______ be him． He is studying in the classroom．（ ）
A．needn'tB．mustn'tC．shouldn'tD．can't