名词性物主代词mine/yours/his/hers/theirs — 英语选择题
题目
放学后，教室里有四个书包：黑色、蓝色、绿色、红色。Oliver 说：'The black bag is mine.' Sarah 对 Amy 说：'The blue bag is yours, Amy.' John 指着绿色书包说：'That green bag is his.'（his 指 John 自己的）已知剩下的红色书包是 Mike 丢的。请判断：蓝色书包是谁的？
A. It's Sarah's. B. It's Amy's. C. It's John's. D. It's Oliver's.