动名词可以在句子中充当主语，通常表示一种抽象的行为、状态或想法。以下是一些动名词作为主语的例句：
Reading is an art.
Smoking is prohibited here.
Climbing mountains is really fun.
Doing much exercise is good for our health.
Swimming is a good sport in summer.
Listening to the music is good.
Throwing litter about is very bad.
Milk is good for your health.
Please give me a hand.
It is no use crying over spilt milk.
It is a waste of time persuading such a person to join us.
There is no saying when he'll come.
No smoking.
No parking.
Their coming to help was a great encouragement to us.
Does your saying that mean anything to him？
这些例句展示了动名词在不同句子结构中的用法，包括直接位于句首、用 it 作形式主语、用于“There be”结构中以及动名词的复合结构等。希望这些例子能帮助你更好地理解动名词作为主语的使用。