快递运单是（）与快递企业之间的寄递合同。
A、收件人
B、寄件人
C、承运人
D、业务员
参考答案：B
金属因介质的侵蚀作用而受到损坏的现象叫做金属腐蚀。金属抵抗各种侵蚀的能力叫做金属的耐腐蚀性能。
—Why was he late for school yesterday?
— He overslept. By the time he got to the bus stop, the bus ________ already ______.
A．has; left
B．had; left
C．was; leaving
D．have; left
