1)关系代词的选择，主要是指who and that;that and which;as and which这三对关系代词的选择。
a.who 可以代表人、人格化了的动物、神话故事中的人物或有生命的事物，例如：
The dog who is barkig to our pet.
2)在从句中作主语时，倾向于用who,如 Do you know the comrade who spoke just now?
3)当先行词泛指代词he ,they 或指示代词those 等时，常用who eg:
He who does no gets no pay.
