选词填空 This isn' my book.That is ____ book.(my,your,his,her,its,their)

问题描述:

选词填空 This isn' my book.That is ____ book.(my,your,his,her,its,their)

可以很肯定是my,因为前面的意思是这不是我的书,后一句说那才是我的书.