1·For if these increases of income or utility are reduced to being infinitesimal, one can use both the symbolism and the powerful manipulations of the differential calculus.
因为，如果这些收入或效用的增加可以化为无穷小，那我们既能使用符号表示，也能利用微分学强大的操作了。
2·Integral upper limit function is a basic concept in function differential calculus.
积分上限函数是一元函数微分学的基本概念。
3·In theory the paper discusses a usage of an important limit formula of differential calculus.
本文从理论上讨论微分学第二重要极限公式的一个使用方法。
4·Limit is the soul of differential calculus, limits' calculation is an important content of the limit theory.
极限是微分学的灵魂，极限的计算是极限理论的重要内容。
5·Maxwell's theory of electromagnetism and Einstein's theory of general relativity are also expressed in the language of differential calculus.
麦克斯韦电磁理论和爱因斯坦的广义相对论也表示的语言微分。