What a pity! I _____ in London for three more days, but something urgent needed to be dealt with back in Beijing.

A．must have stayed

B．could have stayed

C．may have stayed

D．needn’t have stayed

电商企业常用的市场数据分析工具有（）。

A.淘宝指数

B.邮件问卷

C.电话访问

D.街头访问