be (am, is, are) +V-ing 为现在进行时.
现在进行时：表示此时此刻正在进行的动作.
句形：主语+am/is/ are + V-ing
否定句：主语+am/is/ are +not + V-ing
疑问句：Am/is/are +主语+V-ing
特殊疑问句：特殊疑问词(what, when, where...) +be+ V-ing
I'm watching TV.I'm not watching TV.Are you watching TV?
What are doing?
有的时候也有进行时的句式来表示将来时.
I'm coming 我来了.