四，1 .Africa's deserts are expanding fast .Thousands are dying. Millions more are refugees.非洲的沙漠正在迅速扩大，数以千计的人正在死亡，数百万人成为难民。
2 . Scientists have been warning the world about this for many years and if people had acted quickly back then , they would have stopped today's disasters but they did nothing.科学家们为此已经警告人们许多年了如果当时人们可以迅速采取行动他们就能阻止如今的大灾难,但他们却无动于衷。
3 . There is also new fuel technology .Today this runs the world's three billion vehicles ， and it produces no CO2 at all-nor any other kind of pollution我们还有新的燃料技术，如今世界上三十亿辆汽车以此为动力，它既不产生二氧化碳，也不产生任何其他污染。
