不定词=to+动词的原式。例如to go, to love, to eat等等，都是不定词，不定词和动名词的用法相似，以下全是用不定词用作名词的例子：
To love is to forgive.
To forgive your enemies will make you happy.
I like to eat chicken.
I asked my brother to come here.
He continued to read.
*I am interested in to play piano.
*He is worried about to go abroad.
*I am in charge of to prepare for the party.
To play tennis is great fun.
To play safe in the stock market is necessary.
To be kind to others is important for every one.
To respect your parents shows good character.
I like to swim.
He loves to listen to jokes.
My brother seems to be different.
I agree to lend him money.
Do you like to sing?
I told him to work hard.
I asked my brother to come back home.
He expects his friends to help him.
My teacher told me to wait for him.
I invited my sister to go to see a movie.
He was told to work hard.
My brother was asked to come back home.
His friend is expected to help me.
I was told by my teacher to wait.
My sister was invited to go to see a movie.
To give is more meaningful than to receive.
I love to swim in cold weather.
He agreed to listen to my story.
He decided to go anyway.
I told him to buy my book.
I invited him to come to my house.
I asked him to cook for me tonight.
Students are asked to work hard.
He needs to work hard.
I want you to send this letter to my father.
He requires every student to read one novel every week.
Every student is required to read one novel every week.
有些动词后面可以跟动名词或不定词：love, like, hate, start, begin,以下的动词，后面只能跟动名词：
Enjoy I enjoy eating good food.
Appreciate I appreciate your being kind to others.
Avoid You should avoid making mistakes.
keep on Keep on working hard.
keep Keep singing.
consider He considered leaving home.
finish He finished writing this book.
suggest May I suggest drinking a cup of coffee?
discuss We discussed traveling to New Zealand.
agree I agree to sign this letter.
plan He plans to go away.
want They want to rent a car.
decide He decided to work hard.
seem He seems to be very happy.
appear He appears to be very sad.
stop smoking 指不再抽烟了
stop to smoke 指停下来，开始抽烟