每年的7月11日为世界人口日。目的是唤起人们对全球人口问题的关注。1987年，世界人口提前两年达到50亿，同年设立世界人口日。该节日由联合国开发计划署理事会发起，此后每年设立宣传活动，警告人们人口过剩的危险性。这些问题包括水资源短缺，食物供给不足，污染加重，以及因资源短缺而导致的贫困和战争。在这一天，联合国以及各国政府将在学校和当地社区展开教育活动。为数十亿人口的生存，我们需要行动起来。

World Population Day focuses on sustainability and how to improve the lives of all people while protecting the Earth’s resources. Overpopulation refers to the point when the Earth does not have enough resources to feed everybody. Overpopulation can exist even in deserts where very few people live if there aren’t enough resources to sustain them. These resources include clean water, food, shelter, and clean air. There are many reasons why the Earth is becoming overpopulated today. Perhaps the biggest one is advances in medical science. Greater numbers of people have access to better health care and more cures have been found for killer diseases. We need to think more about how we use the Earth’s resources.

世界人口日侧重可持续发展，以及如何在保护地球资源的同时提高生活质量。一旦地球资源无法供给人类需求，那么就出现了人口过剩问题。即使在人口数量少的沙漠，若资源不足也会产生人口过剩。资源包括清洁水资源、食品、居所以及清洁空气。造成今天人口过剩的原因有许多。最主要原因就是先进的科学技术发展。享受完善医疗体系的人口越来越多，许多疾病已不再致命。对于如何使用自然资源，我们还需要考虑清楚。

1.refer to 指的是

例句：He never referred to his sisters in his letters.

他在信里从未提到过他的姊妹。

2.focuse on 集中于

例句：Our meeting focuses on the question of women's right.

我们会议的重点是妇女权利问题。

3.health care 卫生保健

例句：Nobody wants to pay more for health care.

没人愿意为医疗保健花更多的钱。

4.warn of 警告

例句：The government warned of the storm.

政府预告说有暴雨。