by Montgolfier in the late eighteenth century, and the balloon becomes a sort of symbol of perhaps liberty.

在十八世纪末发明的,而从此热气球也成了某种自由的象征

耶鲁公开课 - 1871年后的法国课程节选

The beginning of the problems with CO2 and global warming.

二氧化碳和全球变暖的问题2,也从此产生。

麻省理工公开课 - 热力学与动力学课程节选