Then she said goodbye to her old parents and gave them a speical long-life medicine as a goodbye
问题描述：
Then she said goodbye to her old parents and gave them a speical long-life medicine as a goodbye
gift .The old parnets lived a long life after （ ）空格答案是that,我填了it,为什么不对啊
答
that指上文,而it不能,再如
---He was punished by his parents.
--- When was that happened?it不是可以指代句子吗,而且that不是只能指代上文的单数名词that 指上文的事，而it常指一同类同物的名词。如 I bought a book and it is very interesting.那it可不可以指代上文的一个句子一般不可.