题目内容：

【初二英语】【句型】They were mending Englishi at that time.（改为否定句）并说明理由!
请回答者说明理由!
They were mending English at that time.（改为否定句）
They_____ _____ _____English at that time.

优质解答

They were mending English at that time.（改为否定句）
They（were）（not） （mending） at that time
句子中已有were（be动词过去式）,只要在Be动词后加not便解决了