Unit 4 我爱记单词-语境记忆法
1. According to biology, humans, lions and whales are mammals. In general, female mammals give birth to babies rather than lay eggs, and feed their young with milk. 根据生物学（理论），人类、狮子和鲸是哺乳动物。

一般情况下，雌性哺乳动物生产幼仔而不是产卵（繁殖），并用奶来喂养后代。

2. As everyone knows, everything in the world is composed of atoms. The atmosphere contains oxygen, nitrogen carbon dioxide, water vapour and other gases. Oxygen and water are fundamental to all living things on the earth.
众所用知，世界上的一切都是由原子组成的。

大气中含有氧气、氮气、二氧化碳、水蒸气和其他气体.氧气和水对于地球上一切生物都是至关重要的.
3. Later, the first tiny plants began to appear and multiplied in the sea; then early shellfish developed. Next green plants began to grow on land, and they were followed in time by land animals such as insects and amphibians. Still later, reptiles appeared for the first time. After that huge dinosaurs developed, too. They existed on the earth for over 140 million years. They became extinct probably because an unexpected incident broke out.
后来，最早的微小植物开始在海洋里出现并繁殖；然后早期的水生有壳动物也孕育了。

接下来，绿色植物开始在陆地上生长，及时跟随其后的是陆地动物，如昆虫和两栖动物，再后来，爬行动物第一次出现了。

之后，巨大的恐龙也孕育出来了，它们在地球上生存了一亿四千多万年。

它们的灭绝可能是因为一个意外事件的爆发。

4.My friend John is now studying astronomy at college and wants to be an astronomer after graduation. Unlike other students, he once questioned whether there were eight planets in the solar system. He believed in religion, and even put up a theory quite different from the “Big Bang”.
我的朋友约翰正在大学里学习天文学，大学毕业后他想当一名天文学家。

跟其他学生不同，他曾经质疑过在太阳系中是否有八颗行星。

他过去信仰宗教，甚至提出了一个和“宇宙大爆炸”完全不同的理论。

5. Recently, in order to work out the puzzle of climate warming, J many physicists, biologists and geologists attended an important meeting. They discussed how to
prevent human beings from putting too much carbon dioxide into the atmosphere. Now that this is a man- made problem, man should solve it himself.
最近，为了解决气候变暖的难题，许多物理学家、生物学家和地质学家出席了一个重要会议。

他们讨论了如何阻止人类把太多的二氧化碳排放到大气中（的问题）。

既然这是一个人为的问题，那么，人类就应该自己解决它。

6. Several billion years after the “Big Bang”, the earth finally turned from a violent cloud of dust into a solid globe. Then the presence of water, many scientists believe, allowed the earth to dissolve harmful gases and acids into the oceans and seas. This produced a chain reaction, which made it possible for life to develop.
“宇宙大爆炸”数十亿年后，地球终于从一团猛烈的尘埃变成了坚固的球体。

许多科学家认为，之后水的出现，使得地球；把有害气体和酸性物质溶解在海洋里。

这便产生了连锁反应，使生命的孕育成为可能.
7. Once, a comet crashed on the earth and then exploded; the explosion made the smog and steam float in the air for some time, blocking out the sunlight.
有一次，一颗彗星撞在地球上，然后爆炸了；这次爆炸使得一段时间内，烟雾和蒸汽漂浮在空气中，阻挡了阳光。

8. The following is a fictional story. Once upon a time, there were three great scientists named Isaac Newton, Albert Einstein and Stephen Hawking, who traveled in the cabin of a spaceship to the moon. They cheered up because they wanted to feel how the pull of the earth's gravity would change during their journey. Besides, they observed stars and planets by analyzing the information sent by the satellite. During the whole trip they in their turn watched out for any possible change.
以下是一个虚构的故事。

从前，有三位伟大的科学家，名叫艾萨克•牛顿、阿尔伯特•爱因斯坦和斯蒂芬•霍金，他们坐在一艘宇宙飞船的舱里到月球去旅游。

他们欢呼雀跃，因为他们要感受一下地球引力在他们旅程中会如何变化。

此外，他们还通过分析卫星传送的信息来观察恒星和行星。

在整个旅程中，他们轮流观察任何可能的变化。