When she had departed, they fell to fighting among themselves.她走后, 他们便打了起来。
He fell to wondering if it was true.他开始怀疑事情是不是真的。
英汉双解词典包含368430条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。