When to use the intinitive

FROM: www.englishclub.com (the "black information")

When to use the infinitive

The infinitive form is used after certain verbs:
- forget, help, learn, teach, train
- choose, expect, hope, need, offer, want, would like
- agree, encourage, pretend, promise
- allow, can/can't afford, decide, manage, mean, refuse

• I forgot to close the window.
• Mary needs to leave early.
• Why are they encouraged to learn English?
• We can't afford to take a long holiday.

The infinitive form is always used after adjectives, for example:
- disappointed, glad, happy, pleased, relieved, sad, surprised

• I was happy to help them.
• She will be delighted to see you.

This includes too + adjective:

• The water was too cold to swim in.
• Is your coffee too hot to drink?

The infinitive form is used after adjective + enough:

• He was strong enough to lift it.
• She is rich enough to buy two.