i agree with ... thinks people need/don't need ... because ... i am sure people can't /will be happy without ... Надо место ... поставить слова. да и чтоб подходили по смыслу.

I agree with the statement that our planet is in danger. People need take care about our planet, because it is the wonderful place to live.  I'm sure people can't be happy without clear air and water, green parks and forests.  So,we must not pollute our planet.