No matter what he does， every person on earth plays a central role in the history of the world. And normally he doesn't know it.
无论他做什么，地球上的每个人在世界历史中都扮演着核心角色。而通常他并不知道这一点。
The anarchic nature of the international system means that states must rely on self-help to ensure their survival.
在科学中最令人兴奋的短语，预示着新发现的，不是“我找到了！”而是“这有点奇怪……”