资料内容：
In Section 1.6，we will see that this result about complements alwags holds forprobability,even when we go beyond the naive definition. A good strategy whentrying to find the probability of an event is to start by thinking about whether it willbe easier to find the probability of the event or the probability of its complement.De Morgan's laws are especially useful in this context，since it may be easier towork with an intersection than a union, or vice versa.
