设().
参考答案：4
解析：
— Whose watch is this? Is it _________?
— No, it's not __________ bike. It's _________.[ ]
A. yours; mine; her
B. your; my; hers
C. you; my; hers
D. yours; my; hers
给出关系R和S，如下表。如果要得到关系D需要执行哪个操作
().
().