_____the Internet is of great help, I don’t think it’s a good idea to spend too much time on        it.

A．If

B．While

C．Because

D．As

蛛网膜下腔阻滞术中最常见的并发症是（）。

A.呼吸抑制

B.心律失常

C.血压下降

D.头痛

E.全脊髓麻醉