不定式和动名词作主语的区别：
(1)动名词作主语通常表示抽象动作；而不定式作主语表示具体动作.
Smoking is prohibited(禁止)here．这里禁止抽烟.(抽象)
It is not very good for you to smoke so much．你抽这么多烟对你身体很不好.(具体)
(2)动名词作主语时,通常用以表示一件已知的事或经验.
不定式短语通常用来表示一件未完成的事或目的.
Climbing mountains is interesting．爬山很有趣.(经验)
Driving a car during the rush hour is tiring．在高峰时刻开车令人厌烦.(经验)
(3）不定式做主语,一般用it当形式主语,把作主语的不定式短语后置.
It took me only five minutes to finish the job.