英语介词grateful to him 和 afraid of him 为什么介词of 和to 区别 前面也都是形容词崇

表示“害怕做某事”或“不敢做某事”,be afraid 之后可接不定式,也可接 of doing sth.如：
She was afraid to tell [of telling] you. 她害怕告诉你.
She is afraid to go [of going] out alone late at night. 她很怕深夜独自外出.
但若要表示担心可能会发生某事,则只能用 be afraid of doing而不能用 be afraid to do.如：
She is afraid of lagging behind the others. 她怕落在别人后面.
She didn’t tell him because she was afraid of upsetting him. 她没有告诉他,因为怕他不安.
感激某人因某事
感谢,感激
be: vi. 1.有…存在,生存. Can such thin ...
grateful: adj. 1.感恩的,感谢的. 2.愉快的,爽快的;可喜 ...
to: adv. 到某种状态；〔特指〕到停止状态；关闭. ★也常 ...

固定用法 这个没什么好解释 词法记住就行 谢谢采纳

to 表示目方位，即动作的指向；
of　引导动作作用的对象，即动作作用在什么身上。