The black box is a necessary device on an airplane, which records its speed, direction and whether

everything on the airplane _____ normally.[ ]

A. will function

B. functioned

C. is functioning

D. has functioned

下面哪些企业推出了“线上下单、线下自提”的网络营销策略（）

A.当当

B.苏宁易购

C.京东商场

D.戴尔

E.艺龙网