如何填写英文这些句子?原文：we must keep the air clean for the eagle to fl

如何填写英文这些句子?
原文：
we must keep the air clean for the eagle to fly.
we must clean up our oceans so the whales can swim
by.
I think we should fight for our water and sky.
We must help our Earth.
I believe we must try!
How should we protect plants and animals?work with your class to think of ideas.Finish each sentence below.
1.we should____.
2.we must_____.
3.I believe that_____.
4.I think that_____.