下列哪些是二尖瓣关闭不全的常见原因()
A. * * 肌功能不全
B.收缩期高血压
C.二尖瓣脱垂
D.感染性心内膜炎瓣叶破坏
E.腱索自发性断裂
参考答案:A, C, D, E
I don't think a warm winter always has a negative influence on our life, _____?
A.do I
B.does it
C.hasn't it
D.don't I
中国的基本政治体制是( )
A.人民代表大会制度
B.多党
C.群主立宪