世界上最好和最美丽的东西是看不见甚至摸不到的 - 它们必须用心去感受。
煤炭的可持续未来取决于我们能否在不牺牲依赖该行业的人的生计的情况下整合更清洁的做法。
The fundamental point in fabricating a chain reacting machine is of course to see to it that each fission produces a certain number of neutrons and some of these neutrons will again produce fission.