this意为这；that意为那；介绍近物用this，介绍远物用that。
例句
This is a computer. 这是一台电脑。
That is a bike. 那是一辆自行车。
This is a book. That is a pen.
这是一本书，那是一枝钢笔。
That\'s where you are wrong.
这就是你不对的地方。
Look at that guy. He\'s got red socks.
看那家伙，他穿着红袜子。
That\'s my wife you were talking to.
刚才和你说话的是我妻子。
