1. Continuous progressive: Basically express something that is happening at that moment or say something that is happening for a limited time.

2. Subject / object: The subject of the sentence is the person / thing that performs the action and the object is the one that receives the action.

3. After preposition: Indicate the place, time, moment and purpose.

4. Adjective: Adjectives respond to how it is.

5. After some verbs: When we should use the gerund after a verb.