按要求句型转换:Mary was riding a bike at that time

问题描述:

按要求句型转换:Mary was riding a bike at that time
否定句
一般疑问句
两个回答
特殊疑问句

Mary wasn't riding a bike at that time.
Was Mary riding a bike at that time?
Yes,she was./No,she wasn't.
What was Mary doing at that time?