Here are the corrections for each statement:

4. **"My uncle is one of the best environmentalists in my country."**
- Correction: "environmentalist" should be "environmentalists."

5. **"People should keep a fire extinguisher in a safe place."**
- Correction: "extinguish" should be "extinguisher."

6. **"If you are in danger, call the emergency service; they can help you."**
- Correction: Change "calling" to "call" and use a semicolon instead of a comma.

7. **"Outdoor activities can make people healthier."**
- Correction: "Outdoors activities" should be "Outdoor activities."

8. **"Julia usually watches action movies when she feels sad."**
- Correction: "action movie" should be "action movies."

9. **"We'd like to announce that the village festival will take place from January 21st to February 2nd."**
- Correction: Add "that" after "announce" and change "on" to "from."

10. **"All the children are interested in the animal performance at the festival."**
- Correction: "perform" should be "performance."

11. **"If you don't pay attention, you will not understand the lesson."**
- Correction: "will understand" should be "will not understand."

12. **"It is too hot today - please turn on the air conditioning."**
- Correction: "air condition" should be "air conditioning."

13. **"Governments worldwide are working together to protect the environment from pollution."**
- Correction: "for pollution" should be "from pollution."

Feel free to ask if you need further assistance!