Everyone says I must be mad and they are probably right.________they are.
问题描述：
Everyone says I must be mad and they are probably right.________they are.
(a) Of course (b) It's certain (c) Perhaps (d)It's sure
答
C
A of course 不能引导句子
B It's certain that 加句子,少了that不行
D 和上面道理一样,少了that