Where is your pen pal from?这边用的是is.那为什么What are your sister doing是用are呢?
问题描述:
Where is your pen pal from?这边用的是is.那为什么What are your sister doing是用are呢?
答
因为What are your sister doing错了
What is your sister doing才对,你姐姐是第三人称单数