What kind of natural resources can you think out? 你能想到哪些自然资源呢？

　　We can easily think of oil, coal, gold and iron. 我们可以轻易地想到油、煤、黄金和铁。

　　These usually come from under the ground. 这些资源通常是在地下。

　　Air, water and wind are also natural resources. 空气、水和风也是自然资源。

　　Natural resources are limited. 自然资源是有限的。

　　If people use up all the natural resources, there will be no more of them in the future. 如果人们把所有的自然资源都用光了，未来就不会再有了。