My mind raced as I tried to work out what was happening.

　　我拼命地轉動腦筋，想要搞清楚發生了什么事兒。

　　She couldn't believe it was all happening again.

　　她簡直無法相信整件事又在重演。

　　I heard a commotion and went to see what was happening.

　　我聽到一陣喧鬧便去看看發生了什么事情。

　　There is very little likelihood of that happening.

　　幾乎沒有發生那種事情的可能。

　　We hope to prevent anything unpleasant from happening.

　　我們希望防止任何不愉快的事發生。

　　I saw what was happening, but I was powerless to help.

　　我眼看著事情發生，卻無力相助。