一般that 远指,或指代上文
this近指,或指代下文那问一个问题— You come from England, don't you?— ______ How do you know that?A. No, I doB. No, I don'tC. Yes, l amD. Yes, I doD。that 指上文所提之事如果that改为this呢then it is not correctwhy……因为this指下文啊，下文不是还没有吗