During the period of recent terrorist activities, people _____ not to touch and unattended bag.

A．had always been warned

B．were always being warned

C．are always warning

D．always warned

商业银行的信用卡收单业务主要包括（）。

A.审批授信

B.资金垫付

C.商户资质审核

D.交易授权

E.获取交易授权