生产如此数量的粮食可能大大提高环境中二氧化碳和氮的水平，引起很多物种的灭绝。
Producing that amount of food could significantly increase levels of carbon dioxide and nitrogen in the environment and cause the extinction of numerous species.
他们表示，人口减少可能是件幸事：生活水平将继续提高，而拥挤状况和环境方面的压力将有所缓解。
They say fewer people may be a blessing: growth in living standards will continue while congestion and pressure on the environment will be eased.
改善水、环境卫生和个人卫生的努力可相互作用，提高整体健康水平。
Efforts to improve water, sanitation and hygiene interact with each other to boost overall health.
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