下面哪项不是原发性下肢静脉曲张的病因()。
A.先天性静脉壁薄弱
B.静脉瓣膜损坏
C.经常参加游泳训练
D.从事长期负重劳动
E.长期站立工作
参考答案:C
偏头痛最常见的类型是哪型?临床表现如何?
Honesty is generally considered the best policy ________ you are stopped by the police at the
accident spot. [ ]
A. in case
B. even if
C. so that
D. only if