hang by a thread be in a highly precarious state.
lose the (or your) thread be unable to follow what someone is saying or remember what you are going to say next.
pick up the threads: seepick.
英语词组固定搭配大全包含15956条英汉双解词组,基本涵盖了全部常用英文词组、短语的翻译及用法,是英语学习的有利工具。