Verb+verb in gerund / verb+ verb in infinitive/ verb{verb in erund or infinitiva

If there are two verbs together in a sentence, often the second one is either in the infinitive form (to play) or the continuous form (playing).  Have a look at this example, only one of thesentences is correct:
·       I enjoy to play piano X
·       I enjoy playing piano √
a. We use the infinitive after certain verbs:
               - forget, help, learn, teach, train               -choose, expect, hope, need, offer, want, would like
               -agree, encourage, pretend, promise, recommend
               -allow, can/can't afford, decide, manage, mean, refuse
Have a look atthese examples:
* You forgot to water the plants.
* I can’t decide what to wear.
* We promise to help you if we can.
* I hope to see you again soon.
b. We also always use theinfinitive after adjectives:
- happy, sad, sorry, disappointed, angry, pleased, delighted, glad, surprised, relieved etc.
               Have a look at these examples:
* I was sorry to hear aboutyour recent troubles.
* I’m happy to hear from you.
* She was angry to discover Charles was lying to her.
* We’re delighted to have you here in our home.
* They were relieved to knowit was all over.
c. This is also the same for the form too + adjective:
               - too cold, too hot, too windy, too sunny, too salty, too sweet etc.
Have a look at these examples:
*This tea is too hot to drink.
* It’s too windy to go for a swim today.
* This soup is too salty to eat.
* My feet are too sore to walk anymore.
d. The infinitive is also used with theform adjective + enough.
               - rich enough, clever enough, strong enough, tall enough, short enough etc.
Have a look at these examples:
* Are you tall enough to touch the ceiling?* My four year old son is clever enough to read short novels.
* Will this glue by strong enough to fix the window?
* This sandwich is big enough to have for dinner!...