问题描述：
before后的时态问题
My mother often takes a long walk before ______(go) to bed.
答案是going 为什么?before在这里做什么成分?
My mother often takes a long walk before ______(go) to bed.
答案是going 为什么?before在这里做什么成分?
问题解答：
我来补答展开全文阅读