happen|happens|happened|happening

碰巧，她的生日在我的生日之后一天。

As it ___happens, her birthday is the day after mine.

碰巧，我正在为自己找计算机课程，想参加你们的一个课程。

As it ___happens, I am currently looking for a computer course for myself and I would like to join one of your courses.

碰巧，我们刚才正在谈论你。

As it ___happens, we were just talking about you.

你听说昨晚我们发生了什么吗？

Did you hear what ___happened to us last night?

你今天在学校发生了什么事？

What ___happened to you at school today?

我们经常谈论白天发生在我们身上的事情。

We often talk about what ___happened to us during the day.

发动机里正发出奇怪的噪音。

There is a strange noise ___happening in the engine.

尽管科学家努力确保万无一失，事故仍然可能发生。

Although scientists try to make sure nothing goes wrong, accidents can still ___happen.