* Formula: Be + verb + present participle
* Example: I am swimming.
* Usage: The present progressive is used to describe actions that are happening right now.
2. Past progressive:
* Formula: Was/were + verb + present participle
* Example: She was running when she tripped.
* Usage: The past progressive is used to describe actions that were happening in the past.
3. Future progressive:
* Formula: Will be + verb + present participle
* Example: The train will be arriving at 5 pm.
* Usage: The future progressive is used to describe actions that will be happening in the future.