题目

There was a loud knock at the door.(用时间状语从句合并成一个句子)
She was answering the telephone.There was a loud knock at the door.(用时间状语从句合并成一个句子)

提问时间：2020-08-03

答案

There was a loud knock at the door when she was answering the telephone.
加一个引导时间状语的词或词组即可.