吗啡的镇痛作用是由于（）。

A.抑制外周感觉神经末梢

B.抑制脑干网状结构上行激活系统

C.激动第三脑室及导水管周围灰质的阿片受体

D.抑制中枢的阿片受体

E.抑制大脑边缘系统

Jane_____TV with me at about eight yesterday evening. [ ]

A. is watching

B. was watching

C. has watched

D. had watched