Read the passage and fill in the blanks with proper words.

    Everyone knows that trees are very important to us. F of all, trees do good to our health. They give out oxygen(氧气). We can't live without trees. Secondly, trees can m the world more beautiful. Trees are so important to us that we must p more trees. And we must d our best to look a them and we can't destroy (破坏) them.