The country's railway system has launched online ticket-booking and a real-name ticket purchasing system, and _______ requires passengers to provide their ID numbers when buying tickets.
第一节:单项填空(共15小题;每小题1分,满分15分)
从A、B、C、D四个选项中,选出可以填入空白处的最佳选项。
--- How long are you staying?
--- I don’t know. .
A. That’s OK. B. It depends. C. I am going. D. It’s doesn’t matter.