在NLP的沟通技巧中，以下哪项最能有效减少对方重复观点的次数？

在设计类的继承层次时，为什么顶层父类应该尽量抽象？

Which tense is used when describing an action that was happening at a specific time in the past?

Which conjunction properly introduces the reason in this sentence: '______ representative government requires informed citizens, the report emphasizes education.'?

在Java中，假设存在一个名为`Employee`的父类和一个名为`Manager`的子类，`Manager`类重写了`Employee`类的`work()`方法并新增了`meeting()`方法。如果先创建一个`Manager`对象并将其赋值给`Employee`类型的引用变量`emp`，然后将`emp`强制类型转换为`Manager`类型的引用变量`man`，那么以下哪个说法正确？