如何辨别要用is are weren't wasn't were

如何辨别要用is are weren't wasn't were
如何辨别要用is are weren't wasn't were

如何辨别要用is are weren't wasn't were
前两个现在时,表示现在的状态,后面过去时,表示过去的状态.单数用一四,复数,你和虚拟语气用二五