1、动词不定式和动名词做主语的区别：
不定式：强调具体的、一次性的动作 如：to learn an art is very hard.学习一门艺术很困难.
动名词：强调多次的、抽象的动作 如：working in these conditions is not a pleasure.在这种条件下工作一点也不愉快.
通常用It做形式主语来使句子更加平衡：
It is very hard to learn an art.
It is not a pleasure working in these conditions.