fell后面加什么介词

　　The men at the table fell about laughing.

　　一桌人都笑得直不起腰来。

　　Dan fell about and slapped his thighs

　　丹笑得前仰后合，直拍大腿。

　　We fell about at grandpa's funny story.

　　听了爷爷讲的滑稽故事，我们忍不住大笑。

　　He fell to thinking about the early days and his lost friends.

　　他开始思念起他早年的时光和失去的朋友。

　　I acted badly in class, and I fell sorry about that now.

　　我在课堂上表现不好,现在对此我感到很抱歉。