当主语为非第三人称单数，如： I / you / they/ we 等时用have
如： We have a big classroom.
I have waited for you for about two hours.
但主语为第三人称单数，如： he/ she/ it 等时用has
如： My sister has a nice watch.
Tom has already finished doing his homework.
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追问My sister has a nice watch.这句为什么不用is 呢，有什么区别？
追答我姐姐有块好看的手表。
有 当然用 has了， 而is “是”就翻译不通了哟