含义丰富的this

【观察】

本课中出现了很多含this的句子，请大家先观察一下this在这组句子中的用法。

1. In some areas in Shanxi Province, this has destroyed almost all the land ．．．

2. This helps to develop local economies.

3. Just think: all this started with 5 yuan!

【用法归纳】

以上句子中的this是代词，指代前面提到的事情。句1中this指代前一句中的"serious erosion of the land"； 句2中this 指代前面两句提到的 "local farmers can grow crops to make a living"和 "With the money they earn from their crops, farmers buy goods or services"；句3中this指代前面提到的植树计划所取得的成绩。由此可以看出，要想理解this指代的内容，必须联系上下文。同时，这也是阅读中经常用到的一种策略。

【拓展】

① this可以有启下的作用，意为"以下所述，如下"。如：

Now, listen to this.

This is going to surprise you.

② this还可以用于口语中，具体为：

a) 用于介绍某人。如： Sam, this is my sister, Liz.

b) 打电话用语。如：This is Joan speaking.

③ this也可以作副词，相当于so。如：

The table's about this high and this wide.

You need to cut about this much off the end of the pipe.