Nick :    Ah, welcome back. Let's learn about       
           pollution. We all face the problems
           of pollution. Do you know why ?
Geoff :  No, why is that ?
Nick   :  Well, pollution changes the conditions that we
            depend on . Polluted air makes us sick.
Devi :    It's bad for our health.
Nick :     Let's go.     
Pollution changes conditions
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