1. He sold the idea, now called a vacuum cleaner（真空吸尘器）, to a man named William H. Hoover. The company is still making Hoover vacuums and we're a little bit cleaner for it.
    他把这项现在叫做真空吸尘器的发明卖给了一个叫威廉·H·胡佛的男子。他的公司至今仍在制造胡佛牌真空吸尘器，我们的环境也因此而变得干净些了。

2. As a result, air would be cleaner than in today´s cities.
    因此，空气会变得比现今城市里的空气还洁净。

3. Frankly, I'm proud. I'm doing an essential task. I left this country a little cleaner than I found it this morning. Not many people can say that tonight.
    说实话，我感到骄傲，我在做一项必不可少的工作。每晚工作结束时，我发现这个国家比早上更干净了。并不是每个人当晚都能这样说的。