Some of my friends are interested in science， but none of them can tell ________.
A. when UFOs appeared next time
B. that horses know the way or not
C. where was this kind of plant found
D. how elephants communicate
—These days， teenagers often have to do what they ______ to.
— It’s not good for their independence. They need to think on their own.
A. tell
B. are telling
C. are told
D. were told
The number of the cars ________ greatly since 2008 in the small town.
A. had increased
B. has increased
C. was increasing
D. increased
The scientists will succeed in their experiment______ they give up.
A. unless B. if C. after D. until
Michael’s mother never makes him______his room. He does it by himself.
A. cleaningB. cleans C. to clean D. clean
Jill_______be in the office now. She has gone to the reading room.
A. can’t B. mustn’tC. needn’tD. shouldn’t
