里根就挑站者号航天飞机失事悲剧英语演讲稿：悼念先烈，铭记历史，勇攀高峰

里根就挑站者号航天飞机失事悲剧英语演讲稿：悼念先烈，铭记历史，勇攀高峰Ladies and gentlemen,It is with a heavy heart that we gather here