为提高城市的空气质量，采取的切实可行的措施有哪些？（至少写两条）

阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

For many years, volunteers, both young and old, have been helping the poor and elderly people of this area. They work long hours building wheelchair paths, fixing leaky(有漏洞的) roofs and repairing the homes of those____ need help. Their only payment is the happy smiles and grateful hearts of the people whom____have helped.

I will always remember one man in particular____he has a real enthusiasm for voluntary work. He seemed to have inspired all the people in his group with his____(cheer) spirit. Every day when I asked him____he was doing, he would reply, “I'm doing good!”____the end of the month as he was preparing to leave, I looked at all the homes he ____(fix) and had to agree that he was indeed doing____good job!

A nice house, a successful career, and a lot of money might be nice to have, but____(compare) with fixing others' home and helping those who are in need, their____(significant) is not so great.