课时一　必然事件、不可能事件、不确定事件我们把事件分成三大类 :必然事件 ,不可能事件和不确定事件 (又称随机事件 ) ,所谓必然事件 ,就是指必然发生的事情 .例如 ,人体内含有水份 ,这是必然事件 ,所谓不可能事件 ,就指一定不发生的事情 .例如 ,地球上没有水 ,这是不可能事 Class Hours: An Event, Impossible Event, Uncertain Event We classify events into three categories: Necessary Events, Impossible Events, and Uncertain Events (also known as Random Events). The so-called inevitable events refer to events that necessarily occur. For example, The human body contains water. This is an inevitable event. The so-called impossible event refers to something that must not happen. For example, there is no water on Earth. This is impossible.