作用是控制光线在感光片上停留时间长短的是(  )。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='27861' and id < 2288738 and id<>'2288738' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='27861' and id > 2288738 and id<>'2288738' order by id asc limit 5