英语有几题不会啊!帮帮忙忙

英语有几题不会啊!帮帮忙忙
1.With all this work on hand,he _ to the cinema night.
A must not go
B would not go
C ought not go
D should not have goone
2 The line is busy,someone_the telephone now.
A should be using
B must have beenusing
C uses
D must be using
3 You__qiut your job until you find another one
A had better do not
B had better not to
C the better not to
Dwould better
答案DCD
为什么呢?