二尖瓣狭窄最常见的病因是（ ）。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='30939' and id < 2490347 and id<>'2490347' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30939' and id > 2490347 and id<>'2490347' order by id asc limit 5