T don'tbelieve him he [ ]be serious .括号里填什么

T don'tbelieve him he [ ]be serious .括号里填什么
T don'tbelieve him he [ ]be serious .括号里填什么

T don'tbelieve him he [ ]be serious .括号里填什么
这句子在him后面有逗号吗?
有的话,可填can't.
I don't believe him,he can't be serious.
我不相信他,他不会是认真的.
如没有逗号,那个him是不是多了?
I don't believe he will be serious.
我不会相信他会认真.