虚拟物流要素不包括______。
A．虚拟物流组织
B．虚拟储备
C．虚拟计划
D．虚拟物流服务
参考答案：C
Service was included in the bill, so you _______ the waiter. It was a waste of money.
A．will not tip
B．may not tip
C．needn't have tipped
D．mustn't have tipped
二次函数y= x2 -2x+1与x轴的交点个数是[ ]
A.0
B.1
C.2
D.3
