Here are some complete lines on why we should help the Earth:

1. We should help the Earth because it's our home and we need to protect it.

2. Helping the Earth ensures a healthy and sustainable future for all living beings.

3. By taking care of the Earth, we preserve natural resources for future generations.

4. Protecting the Earth is crucial for maintaining biodiversity and ecosystems.

5. We should help the Earth to mitigate the effects of climate change.

6. Every small action counts in making a positive impact on the planet.

7. Helping the Earth promotes sustainable living and reduces waste.

8. By caring for the Earth, we support the well-being of all living creatures.

9. Protecting the Earth is a collective responsibility that requires individual actions.

10. We should help the Earth because it's essential for our survival and prosperity.

Some possible complete sentences could be:

- We should help the Earth by reducing our carbon footprint and using renewable energy sources.

- We should help the Earth by conserving water, reducing waste, and promoting sustainable practices.

- We should help the Earth because it's our duty to protect the planet and its resources for future generations.

Let me know if you'd like me to come up with more lines!