The conditional element evaluates the Machine instance (which is part of the knowledge) to determine whether the consequences of the rule should be executed.
条件元素对Machine实例(知识的一部分)求值，以确定是否应执行规则的结果。
2
The rule shown in Listing 10 has one conditional element that references a Machine object.
清单10中显示的规则有一个引用Machine对象的条件元素。
3
The first element simply checks for the existence of a Machine instance in the working memory.