例句:They say gas guzzlers are contributing to air pollution.
他们说高耗油汽车是造成空气污染的原因之一。

2.air quality 空气质量

例句:It's unclear whether government vehicles have a huge negative impact on Beijing's air quality.
目前尚不清楚政府公车是否对北京空气质量产生了非常严重的负面影响。

3.at least 至少

例句:He's been away for at least a week.
他走了总有一个星期吧。

4.heart disease 心脏病

例句:It reduces the risks of heart disease.
这降低了患心脏病的风险。