modal auxiliary verb表动词语态的助动词
modal phrasal verb情态短语
modal l verb必须
modal abetting verb表动词语态的助动词
can modal verb能够
Modal Verb Series情态动词连用
will modal verb将
modal verb construction情态动词结构
Modal verb is a comparatively weak point in Chinese research as well as a hard point to foreign students who learn Chinese as a second language.
能愿动词(助动词)是留学生学习汉语的难点，也是汉语研究中相对薄弱的一环。
参考来源 - 对外汉语教学中的能愿动词偏误分析