this, that 指单数,these, those 指复数：this 和 these 指靠近说话者的东西,that 跟 those 指远离说话者的东西
电话用语中，this 指自己,that 指对方：为身旁的两人介绍，都是 this
this, that, these, those 都可和复数(或含有复数含义的)名词连用表示一段时间、一笔钱等
What about that ten dollars you borrowed from me last week？ 你上个星期跟我借的那10元钱怎么样呀？（你打算什么时候还？）
I‘ve been reading the book these two weeks. 这两周来我一直在读这本书。
that 和 those 可以指代前文提到的名词，以避免重复，这时后面总是接有修饰语
His dress is that (= the dress) of a gentleman, but his speech and behavior are those (=speech and behavior) of a clown. 他的衣着是绅士的衣着，可是他的言行是小丑的言行。
用于指代上文内容时，常用 that/those.指代下文时，用 this/these
Health is above wealth; this (= wealth or the latter) cannot give us so much happiness as that (= health or the former).健康胜于财富：后者（财富)不像前者（健康)能给我们那么多的幸福。
this 和 that 还可以用作副词.置于形容词或副词之前表示 so的含义
I can't walk that far (= as far as that). 我走不了那么远。
Can you spare me this mach (= as much as this)？你能分这么多给我吗？
有关this 和that 的惯用语
by this 到了这个时候
at this 一听/看到这一点
with this 于是，一面说着(一西又）for all that/this 虽然如此
That's it. 对的！
That's right.是的。
Is that so？是那样吗？/是真的吗？ That will do. 那正好
onupon this 于是
that is (to say)即，也就是说
That's all 仅此而已。没有了
