the medical certification of the cause of death为死因出具医学鉴定He received his certification as a high school English teacher.他取得了中学英语教师证书.This will serve as certification.以此为凭....
这层大气称为外逸层.This region is called exosphere.在对流层上是平流层, 接着是电离层,最上层是外逸层.Above the troposphere is the stratosphere, followed by the ionosphere and capped by the exosphere....