Americans themselves give varying definitions of the middle class .

美国人自己给出的中产阶层的定义是很不同的。

Charge and current , and magnetic flux and voltage , are connected through their definitions .

电荷和电流，磁通量和电压，根据它们的解释关联在一起。

Definitions of a tax haven vary .

人们对避税天堂的定义各不相同。

This too has made definitions more complicated .

这也使得阶级的定义更加复杂。

And there are at least three key definitions .

目前至少有三种重要的定义。