1.用句型“be afraid that从句”表达“害怕某人做某事”的确可以,不过更简洁的短语是：be afraid of sb/one's doing sth.
2.短语区别如下：
1) be afraid to do sth 因为害怕而不敢做某事
如：I'm afraid to go out alone at night.
2）be afraid of doing sth 害怕会发生某事
如：I'm afraid of being beaten by my father.
3.所以,“害怕某人做某事”应该是使用be afraid of doing sth结构中动名词短语的复合结构即：be afraid of sb/one's doing sth.
其中的sb/one's即人称代词宾格/形容词性物主代词,如果是名词则用其普通格或所有格形式.
如：I'am afraid of him/his getting angry.
I'm afraid of Tom/Tom's getting angry.
我害怕汤姆生气.