vector field的用法和样例：
例句
- The electric current density vector field also satisfies superposition principle, some applications thereof are introduced.
摘要电流密度矢量场也满足叠加原理，给出了一些应用电流密度场叠加原理的例子。 - We shall use various schemes, none of them wholly satisfactory, to depict vector fields in this book.
在本书中我将用不同的图样画出矢量场，但没有一种是完全令人满意的。
