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.
显微镜是永远不会说谎的沉默证人。
我画人不是因为他们是什么样的人,也不完全不管他们是什么样的人,而是碰巧他们就是那样。