Tom's already a little tired,____?用什么反问疑问词？说出为什么？

Tom's already a little tired,isn't he?
Tom 已经有点累了，难道不是吗?

Tom's already a little tired, isn't he ?
这里的's是 is的缩写，反义疑问句用否定形式isn't + he

be tired 是正确形式，所以这里的's是 is的缩写，而不是has(has tired必然是不存在的)
反义疑问句用否定形式isn't + he