1.-how long are you going to ________?

1.-how long are you going to ________?
-for about two weeks.
A.leave
B.be away
C.leave away
D.be left
(答案是B,为什么要选B呢?)
2.-your mother must _______ about you.you'd better go home now.
-not at all.your mother ________ you instead.
A.worry ;is worried about
B.worried ;worry about
C.be worried about ;worrying
D.worried ;worrying
（答案是A,为什么要选A呢?）
3.you just be wrong about that exam.(同义句)
you must be ________ ________ that exam.
（答案是worried about,为什么是worried about)
4.i think ________ necessary for us to read english every morning.
A.this
B.that
C.it
D.one
(答案是C,为什么选C呢?)
5.seeing so many people on the street,tracy stoppped _______ a look.
A.to have
B.have
C.having
D.has
(答案是A,为什么选A呢?)
6.did you have a problem _______ your sister?
A.babysit
B.babysitting
C.to babysit
D.babysits
(答案是B,为什么选B呢?)
7.-how long does it take to go there、
-it depend on_________
A.how do you go there
B.where do you live
C.where you live in
D.how you go there
（答案是D,为什么选D呢?）