2.已知一束单色光在水中的传播速度是真空中的 ,则(    )

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='16641' and id < 1397227 and id<>'1397227' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='16641' and id > 1397227 and id<>'1397227' order by id asc limit 5