1. Verbs followed by the infinitive
1.1. Infinitive form is used after certain form
1.1.1. I forgot to close the window.
1.1.1.1. forgot to close
1.1.2. Mary needs to leave early.
1.1.2.1. needs to leave
1.1.3. Why are they encouraged to learn English?
1.1.3.1. encouraged to learn
1.2. Infinitive form is always used after adjectives
1.2.1. She will be delighted to see you.
1.2.1.1. delighted to see
1.2.2. I was happy to help them.
1.2.2.1. happy to help
1.3. Infinitive form is used after adjective + enough
1.3.1. He was strong enough to lift it.
1.3.1.1. strong enough to lift
1.3.2. She is rich enough to buy two
1.3.2.1. rich enough to buy
2. Verbs followed by-ing
2.1. The -ing form is used when the word is the subject of a sentence or clause
2.1.1. Swimming is good exercise
2.1.1.1. Swimming
2.1.2. Doctors say that smoking is bad for you.
2.1.2.1. smoking
2.2. The -ing form is used after a preposition
2.2.1. I look forward to meeting you.
2.2.1.1. to meeting
2.2.2. They left without saying "Goodbye."
2.2.2.1. without saying
2.3. The -ing form is used after certain verbs
2.3.1. I dislike getting up early.
2.3.1.1. dislike getting up
2.3.2. Would you mind opening the window?
2.3.2.1. mind opening