—What ______ when the earthquake happened on May 12th ?—Er, I was having a geography class in the classroom. A. are you doing B. did you do C. were you doing D will you do
I suggest you delete the useless files on the computer which _______ too much space.
At first I regretted _____ them to stay, but we soon became great friends.
Most of my friends shop at the stores _____ the goods are very cheap.
Weclimbedhigher_____wemightseethescenesbetter.
According to the factory safety rules, all accidents _____ be reported to the safety officer.