Section A 4a答案
1.might be
2.must be
3.could be
4.Can't be
5.could be/must be
Section B 1b答案
a.2 b.3 c.1
Section B 2a答案
so一expressing a result as,because,
since一giving reasons but,however,
though一expressing a difference not only…
but also一adding information
or一giving a choice when,
while一expressing two things happening at the same time
Section B 2d答案
1.and
2.as
3.not only,but also
4.and/or
5.however
Self Check答案
1.can't
2.could/might
3.must
4.might
5.can't