Present Perfect

**Topics Covered in Present Perfect** 1. **Formation**: - Structure: *have/has + past participle*. - Example: *I have seen that movie.* 2. **Usage**: - **Unspecified time**: *She has visited Paris.* - **Experiences**: *Have you ever tried sushi?* - **Duration with "since/for"**: *We have known each other for ten years.* 3. **Key Words**: - *already, yet, ever, never, since, for*. 4. **Common Errors**: - Forgetting *have/has*. - Mixing *since* and *for*. - Using simple past instead of present perfect.