英语有个问题不懂我有个修改题.例如what was he doing while you were cooking the milk?（work in the garden）修改成while i was cooking the dinner,he was working in the garden.书本答案都是while i was,为什么不用while we are啊?谢谢

英语有个问题不懂
我有个修改题.例如what was he doing while you were cooking the milk?（work in the garden）修改成while i was cooking the dinner,he was working in the garden.书本答案都是while i was,为什么不用while we are啊?谢谢