9 年前
视频简介
For two years BBC cameras have followed, Dr Sheperd Doeleman of the Smithsonian Astrophysical Observatory and the work of the Event Horizon Telescope project team, a collective of the top scientific minds from around the world. The project combines radio observatories and telescope facilities from around the world to make up a virtual telescope with a diameter spanning the enti...。在越南战争的最后几天，北越军队节节胜利南越军队则面临崩溃，共产主义的胜利不可避免，美国方面的外交和军事人员接到指示准备撤退，然而他们也意识到，当他们离开后曾帮助并投靠他们的南越盟友将面临生命的威胁。此时他们只能面对这样的道德困境——到底是服从白宫的命令只带美国公民撤离，还是冒着被指控叛国罪的风险尽可能多的保留南越盟友。。
标签
儿童教育
