Theorie:
Study the information about the structure: adjective + to + infinitive.
1. Adjective + to + infinitive
Use this structure with the following adjectives: difficult, easy, hard, impossible, dangerous, safe, expensive, cheap, nice, good, interesting, exciting.
Do you think it is safe to drink this water?
It is interesting to play with Jim.
2. It is nice of you to...
You can use many other adjectives: kind, sensible, sad, amazed, careless, unfair, considerate, silly.
3. I am sorry to/I was surprised to…
Use the structure adjective + to if you want to say how somebody reacts to something.
Other adjectives for this purpose: happy, sad, pleased, disappointed, surprised, amazed, astonished, relieved.
4. Use to after the first, the last, the next, the only, the second.
He is the first to orbit the Earth.
5. Something is sure/certain/likely/bound to happen.
Jim is a good student. He’s bound to pass this test.