Life is like riding a bicycle. To keep your balance (平衡), you ________ keep moving.
A.must B.can C.can’t D.mustn’t
I ________ at the bus stop when I ________ my first teacher yesterday morning.
A.was waiting; met B.waited; was meeting
C.was waiting; was meeting D.waited; met
________ hard, and you will be ________.
A.To study; best B.Study; best C.Studying; the best D.Study; the best
We saw ________ birds when we were climbing the mountain in my home town.
A.million of B.millions of C.millions D.million
—Is that cap Bob’s?
—No, it ________ be his. His is blue.
A.can’t B.mustn’t C.needn’t D.may not
The classroom is ________ small ________ hold (容纳) so many students.
A.enough; to B.so; that C.such; to D.too; to
