As we know ,the earth is gradually becoming warmer and warmer .It's global warming that may be thought highly of by someone ,who always say that it could help the cron grow up such as in a greenhouse .However ,they just pay their attention to the benefits unilaterally ,while ignore the bad effect . I really do not approve of theirs .In my opinion, we must do our best to reduce the greenhouse effect .If we do nothing to control its trend ,just let it tends randomly ,perhaps oneday our beautiful homeland will suffer drought or floods ect .Human beings feel incapable when facing the nature .Consequently ,we must do our best to protect our earth henceforward . Do the little things by ourselves .For example ,do not litter about ,not spit but plant trees .I think it is easy for us to do .If everyone makes a contribution to our earth ,our life would seem better .Use our hands to protect our world !