1、指示代词在作主语时可指物也可指人,但作其他句子成分时只能指物,不能指人,例如:(对)That is my teacher.　那是我的老师。( that作主语,指人)(对)He is going to marry this girl.　他要和这个姑娘结婚。(this作限定词)(错)He is going to marry this.　(this作宾语时不能指人)(对)I bought this.　我买这个。(this指物,可作宾语)2、That和those可作定语从句的先行词,但this和 these不能,同时,在作先行词时,只有those可指人,试比较:(对) He admired that which looked beautiful.　他赞赏外表漂亮的东西。(对) He admired those who looked beautiful. 他赞赏那些外表漂亮的人。(those指人)(错) He admired that who danced well.　(that作宾语时不能指人)(对) He admired those who danced well.　他赞赏跳舞好的人。(those指人)(对) He admired those which looked beautiful. 他赞赏那些外表漂亮的东西。(those指物)3、在回答指示代词作主语的特殊问句时,如果指示代词指人,其回答中的主语仍可以用相应的指示代词,也可以用it或者they;但指事物时,只能用it或者they。 例如:Who’s that? That’s/It’s Liu Dehua.那是谁?那是刘德华。What are those? They are basketballs. 那些是什么?那些是篮球。4、在回答指示代词作主语的一般疑问句时,不管指示代词指人还是指物,答语中都用it或they。例如:Is this a ruler? Yes, it is.Are those your friends? No, they aren’t.5、为避免重复,有时可用 that 或 those 来代替前面已提到过的人或事物;用 this 或 these 来代替下文中将要提过的人或事物。例如:She’s very friendly, and that is why we all love her. 她很友善,这就是我们都喜欢她的原因。You needn’t do this — It’s pretty easy. 你不必做这事,那相当容易。6、向别人介绍某个人时,要说“ This is ….”,而不说“ That is ….”,也不能说“ He is ….”或“ She is ….”。介绍两个人时,先用“ This is ….”介绍一个人,然后用“ That is ….”介绍另一个人。如:This is Li Ming. Li Ming, this is Wei Hua. 这是李明。李明,这是魏华。This is my brother and that is my sister. 这是我哥哥,那是我妹妹。7、one,that 和it的区别:one表示泛指,that和it 表示特指。that与所指名词为同类,但不是同一个,而it 与所指名词为同一个。