modal auxiliary

modal-auxiliary的词性：
n.（名词）

1. One of a set of English verbs, including can, may, must, ought, shall, should, will, and would, that are characteristically used with other verbs to express mood or tense.
情态助动词：一组英语动词中的一个，包括can、may、mast、ought、shall、should、will 和 would， 其特点是与其它动词联用表示语气或时态