1. Uncertain events: There are many things that we are not sure will happen. These things are called uncertain events.

2. Determine that the probability of events is 1, the probability of impossible events is 0, and the probability of possible events is between 0 and 1.

In a game, if every player has an equal chance to win, then the game is fair. Otherwise, the game is unfair.

There are three kinds of events: definite, possible and impossible.

5. In a set of data, the average and median are unique, but the pattern is sometimes not unique. In a set of data, there may or may not be multiple patterns.

6. Understand that the possibility of an event is large or small, and the possibility is related to many factors such as the basic conditions and development process of the event.