GERUNDS AND INFINITIVES
A gerund is a noun made from a verb by adding "-ing."
Example: smoking, swimming, learning, etc
Infinitives are the "to" form of the verb. The infinitive form of "learn" is "to learn."
Examples:
To learn is important. subject of sentence
The most important thing is to learn. complement of sentence
Gerunds can be made negative by adding "not." Example: Smoking is not good for your health.
He enjoys not working.
The best thing for your health is not smoking.
Practice
Examples:
Learning is important. normal subject
To learn is important. abstract subject - less common
The most important thing is learning. normal complement
The most important thing is to learn. abstract complement - less common