心绞痛的病因有（）
A.冠状动脉粥样硬化性狭窄
B.冠状动脉痉挛
C.主动脉瓣严重关闭不全
D.肺栓塞
E.电解质紊乱
参考答案：A, B, C
Is this research centre _____ is full of modern equipment you always mention. [ ]
A. where
B. that
C. the one that
D. the one where
影响出生缺陷的重大危险因素主要有哪些？
