Alex: Hi, David. How was your football match? David: Oh, it couldn't have been ______1______.It was _____2_____ because of heavy ____3______. Alex: That's too bad. When the ___4____ _____5____ is not good, I always wear a _______6______. David: Yeah, but I don't like wearing a mask. It would be _____7_____ to wear a mask while playing football. Alex: You're right. David: I hope the ____8_____ can do something to _____9___ the air quality. Alex: Actually, they've already done a lot in improving the air quality ande dealing with other environmental _____10_____, but I think the most important thing is everyone's ______11_____. Our planet doesn't need _____12_____. It needs ____13______ _______14______. David: Yeah, I agree with you. We must play an active _____15_____ in protecting the environment.