I walked up to the top of the hill with my friends,________we enjoyed a splendid view of the lake. [ ]

A．which  

B．where

C．who  

D．that

原发性头痛是指

A．丛集性头痛
B．脑膜炎头痛
C．脑出血头痛
D．肿瘤性头痛
E．低颅压性头痛