When Harry was having breakfast Lily telephoned him.when后面不是接一般过去时的吗

问题描述:

When Harry was having breakfast Lily telephoned him.when后面不是接一般过去时的吗

也可以接过去进行时,表示当时正在做某事,再如:
When Mum was cooking in the kitchen,there was a knock at the door.