4.happen v.发生，一般指偶然发生，主语为事，不能为人。

　　Sth + happens to sb. A traffic accident happened to his elder brother yesterday.

　　Sth + happens + 地点/时间，意为：某地/某时发生了某事

　　An accident happened on Park Street.

　　Happen v，表示“碰巧”，主语可以是人，后常跟动词不定式to,表示“碰巧……”.

　　Sb + happens to do sth.

　　I happened to see my uncle on the street.

　　* take place 意为“发生，举行，举办”，一般指非偶然性事件的“发生”，即这种事件的发生一定有某种原因或事先的安排。例：

　　Great changes have taken place in China.

　　The meeting will take place next Friday.

　　5.expect v. 期待，盼望，预期，后常接四种结构：

　　1）expect + 名词/代词，期待某事/某人，预计……可能发生。

　　I’m expecting Li Lin’s letter.

　　2）expect to do sth. 预计做某事

　　Lily expects to come back next week.

　　3）expect sb. to do sth.

　　I expect my mother to come back early.

　　4）expect + 从句 预计……

　　I expected that I’ll come back next Monday.

　　6. serious a. 严肃的，认真的。 He is a serious man.

　　be serious about sb/sth. 对某人/某事当真

　　Peter is serious about Jenny. He wants to get married to her.

　　be serious about doing sth. 对某事当真 He’s serious about selling his house.