________ he found the idea interesting, it was too difficult to be of practical use.
A. While B. Once C. If D. Until
As they were walking around, they noticed a man _______ against a tree.
A. sit B. to sit C. sitting D. sat
Do some warming up exercise before sports. Or you _______ hurt yourself.
A. must B. need C. should D. may
Teenagers ________ their sense of hearing because they always wear earphones.
A. damage B. are damaging
C. has damaged D. will damage
What the sick child needs most now ______ love.
A. is B. are C. was D. were
Many people _________ lose one of their senses have made great achievements.
A. who B. whom C. which D. what
