1. Affirmative statement:
I am + v.ing
He/She/It + is + v.ing
We/You/They + are + v.ing
Ex: I am doing my homework at the moment.

2. Negative statement:
Subj + am/is/are + not + v.ing
Ex: She is not (isn't) working in the garden.

3. Interrogative:
Am/Is/Are + Subj + v.ing?
Ex: Are they going to the school concert now?

Usage:
- Actions happening right now.
- Temporary actions.
- Future arrangements.