有：is,am,are,was,were,being,been.

　　现在时Iam,youare,heis,weare,youare,theyare（缩略式I'm,you're,he's,we're,you're,they're）,（否定缩略式I'mnot,isn't,aren't）,过去时Iwas,youwere,hewas,wewere,youwere,theywere（过去时否定缩略式wasn't,weren't）,过去分词been,现在分词being