—I wonder why Susan looks worried today.

—I’m not sure, but she _____a small accident driving here.

A．could have

B．might have

C．might have had

D．must have had

新设立的城市规划编制单位，可以申请暂定资质等级，暂定等级有效期为( )年。

A．1

B．2

C．3

D．4