Not until I came home last night ________ to bed.
A. Mum did go B. did Mum go C. went Mum D. Mum went
Work hard when young, ______ you will regret.
A. and B. so C. but D. or
It’s hot in the shopping mall, because the air-conditioning system ______.
A. broke up B. broke down C. broke in D. broke out
--- It’s the fourth time that heavy smog(雾霾) has hit the city this month.
--- It’s high time we _______ measures to fight air pollution.
A. will take B. took C. to take D. taking
Science has given clear evidence ______ smoking can lead to many diseases.
A. what B. which C. that D. where
We admire this family, ______ the parents treat their child like a friend.
A. why B. which C. where D. that
