自发性SAH病人，其最常见的病因是（）
A.颅内动脉瘤
B.脑血管畸形
C.脑动脉硬化
D.烟雾病
参考答案：A
While watching television, .
A．the doorbell rang
B．the doorbell rings
C．we heard the doorbell ring
D．we heard the doorbell rings
Nancy enjoyed herself so much _________ she visited her friends in Sydney last year.
A．that
B．which
C．when
D．where
