The mass production after World War II had already taken hold.

二战以后的大量生产已经生了根。

耶鲁公开课 - 1945年后的美国小说课程节选

If the vehicle in the unfortunate circumstances of a collision, has to be able to maintain the security of the hydrogen which means more mass, which means a lot of the efficiency is being squandered What's the environmental impact of hydrogen production?

如果车辆,在碰撞中发生了不幸，要仍然能够保持氢气的安全性的话,意味着需要更多的质量，也就是说大部分效率被浪费了,制氢对环境有什么影响呢？

麻省理工公开课 - 固态化学导论课程节选