happen

1. V-I Something that happens occurs or is done without being planned. (偶然地) 发生

We cannot say for sure what will happen. 我们说不准将会发生些什么。

2. V-I If something happens, it occurs as a result of a situation or course of action. (作为结果) 发生

She wondered what would happen if her parents found her. 她不知道如果父母发现了她会怎么样。

3. V-I When something, especially something unpleasant, happens to you, it takes place and affects you. (尤指不愉快的事) 发生 (在某人身上)

If we had been spotted at that point, I don't know what would have happened to us. 如果那时我们被发现了，我不知道我们会有什么后果。

4. V-T If you happen to do something, you do it by chance. If it happens that something is the case, it occurs by chance. 碰巧

We happened to discover we had a friend in common. 我们碰巧发现我们有个共同的朋友。

5. PHRASE You use as it happens in order to introduce a statement, especially one that is rather surprising. 碰巧 (尤用以引出令人意外的内容)

He called Amy to see if she knew where his son was. As it happened, Amy did know. 他打电话给埃米，看她是否知道他儿子在哪儿。碰巧的是，埃米还真知道。