The world is in danger.世界正处于危险中。Our world is in danger.我们的世界正处于危险之中。We must do something to protect the environment. But, what are the main problems we face?我们必须做些什么来保护环境。但是，我们面临的主要问题是什么？The greenhouse effect温室效应The atmosphere around the Earth is necessary for all living things.地球周围的大气层对所有的生物都是必不可缺的。It is like the glass of a greenhouse, letting sunlight in and keeping heat from getting out.它如同那温室的玻璃，只让阳光进入，并（起到）保存热量，阻止热量散失（的作用）。Without it, the Earth would be the same as t
