(2)happen普通用词，泛指一切客观事物或情况的发生，强调动作的偶然性。另外，happen还有"碰巧"之意。

(3)take place"发生，举行"，多指通过人为安排而发生的事。

用occur，happen，take place的正确形式填空

①Did it ever ________ to you that he would go to Australia?

②Great changes ______________ in China since the reform and opening up.

③It ________ that I had no money on me.

答案　①occur　②have taken place　③happened

2．This/That is why. . . 常用句型，意为"这/那就是为什么......"，用来表示事件的结果。

That's why I've come to see you. 这就是我来见你的原因。

Tom came late for the meeting. That was because he was ill.

汤姆开会迟到了，那是因为他病了。

单句语法填空

①That's __________ we were getting anxious about you.

②Tom was late for work this morning. That's ________ he overslept.

答案　①why　②because