Clearly, if I did nothing more, but I took every car, doubled its fuel economy, its emissions would go to 50% of what they are now, no other changes being made.

显然，如果我什么也不做，但是我把没量车的汽油价加倍，汽车废气排放量就会是现在的一半了，别的不会有什么改变。

麻省理工公开课 - 固态化学导论课程节选

The main goal of the respiratory system is to bring fresh in so that you can extract oxygen from it, and blow used air out so that you can rid of carbon dioxide which is the end product of carbon metabolism inside our bodies.

呼吸系统的主要功能是,吸入新鲜空气,以便获得空气中的氧气,呼出废气,以便排出二氧化碳,二氧化碳是人体内碳代谢的终产物

耶鲁公开课 - 生物医学工程探索课程节选