1.动词四中表达中的doing（一人）

  A、做一件事：doing“分词”

        A flying tyger.

  B、做二件事：doing做“进行式”

At half past nine last night, I was doing my homework.

2.一人：have（has、had）

    A、时态~助词

        I have eaten a breakfast now.

    B、情态~动词

        I have to leave。

    C、使役~动词

　　③具有情态动词特征：have(had,has) to,used to, ought to

　　④可做情态动词又可作助动词：如：shall(should),will(would)[1]