主动脉瓣关闭不全的临床表现为()
A.心悸常是最早的表现
B.心绞痛常见,硝酸酯类治疗效果较好
C.早期出现心力衰竭
D.晕厥较主动脉瓣狭窄常见
E.呼吸困难少见
参考答案:A
病例对照研究中,()效率最高
A.1:5匹配
B.1:3匹配
C.1:2匹配
D.1:4匹配
E.1:1匹配
Finally an agreement _________ after they had two-day discussion.
A.reached
B.was reached
C.signed
D.finished