偏头痛的特点为（）。
A.多为轻度疼痛
B.在应用麦角胺后头痛加重
C.头痛部位多在双侧
D.头痛在呕吐后可减轻
E.女性偏头痛与月经期无关
参考答案：D
The road is under construction and that is _____ he hasn't arrived. [ ]
A. the reason at which
B. why
C. the reason which
D. what
干下型室间隔缺损在以下哪两个切面显示最清楚（）。
A.主动脉短轴＋剑突下肺动脉长轴
B.左室长轴＋心尖五腔心
C.胸骨上窝主动脉弓长轴＋胸骨旁左室短轴
D.剑突下四腔心＋左室两腔心
E.右室流入道切面＋心尖四腔心
