动名词短语是由动词加上动名词构成的短语，它们可以在句子中充当主语、宾语或表语等成分。在英语中，动名词短语作为主语的情况比较常见。以下是一些动名词短语做主语的例句：

Traveling is my favorite hobby.

Reading books can broaden your horizons.

Swimming is a good way to keep fit.

Writing the book has taken up all his spare time.

Seeing is believing.

Reading English aloud every day helps improve your pronunciation.

Eating is an important thing.

Watching movies is my favorite pastime.

Reading is one of my favorite hobbies.

Swimming is good exercise for your whole body.

Listening to music helps me relax.

It’s no use sending him over.

It’s too late already.

It’s no good talking to him.

Smoking is prohibited here.

Climbing mountains is really fun.

Doing much exercise is good for our health.

Don't put your bike on the playground.

Milk is good for your health.

Throwing litter about is very bad.

动名词短语作为主语时，谓语动词通常用第三人称单数形式。动名词短语可以表示抽象的、一般性的行为或动作，且常用于表示经常性或习惯性的动作。希望这些例句能帮助你更好地理解动名词短语在句子中作为主语的使用。