1.__be sent to work there?

1.__be sent to work there?
a.Who do you suggest b.Who do you suggest that should
c.Do you suggest who should D.Do you suggest whom should
,为什么不选B?
2.If I had worn my overcoat,I __cold.
A,won't have caught B.won't catch
C.couldn't have caught D.wouldn't catch
答案是C．为什么不选A?
3．-Did you go to watch the football match yesterday?
-No,I didn't feel well,but I would have gone if I __/
a.had b.did c.would.d.was
D怎么不可以?
4.We didn't know his telephone number,otherwise we__him.
A.would have telephoned B,must have telephoned
C.would telephone D.had telephoned
,A怎么不可以
5.He's working hard for fear that he___.
a.should fall behind b.fell behind
c.may fall behind d.would fall behind
答案是A．D和A不都可以表示虚拟么?D为什么不对?