My friend has returned from the UK. She ______ at Oxford for four years, during which we communicated with each other on the Internet.

A．studied

B．has studied

C．had studied

D．has been studying

下列对于颈外动脉的描述哪一项是错误的（）

A.来源于颈总动脉

B.开始在颈内动脉前内侧，继而转到前外侧

C.在颈部有一系列分支

D.上行于腮腺的浅面，形成终支一颞浅动脉

E.暂时阻断颈外动脉，颞浅动脉和颌外动脉均无波动