固定管板式换热器的管壁和壳壁温差在30°C时，一般无须设置波形膨胀节。（） 

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='24910' and id < 2125216 and id<>'2125216' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24910' and id > 2125216 and id<>'2125216' order by id asc limit 5