肺炎链球菌的主要致病因素是（ ）。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='30912' and id < 2487605 and id<>'2487605' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30912' and id > 2487605 and id<>'2487605' order by id asc limit 5