—How many times have you been to China?

—In fact, it is the first time I __________ here.

A．was

B．am

C．had been

D．have been

在进行订单品项数量分析时，首先必须考虑时间的（）。

A.单位和周期

B.范围和周期

C.长短和单位

D.范围和单位