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1、. . . .Unit 3-1 ListeningThere are many forms of lives on earth, including human beings. Life exists in a variety of conditions. Some forms of live live in the watery environment, like the oceans. Other forms of lives can be found in very dry areas like desserts. However, for any form of live to exi
2、st, conditions must be right. When the conditions arent right, that form of lives can extinct. To become extinct means to die out completely. Conditions must be right for life to exist. Millions of years ago, there were forms of lives that no longer exist. When condition changed, this form of life d
3、ied out. One extinction event happened about 250 million years ago. This is the largest extinction event of all time. Many forms of lives become extinct. 96% of all lives in the oceans died out. Most insects also became extinct. This event happened over a period of several million years. The causes
4、of this extinction event are still unknown. Possible causes include largest volcanic eruptions and global warming. Some scientists believe that there were several causes. They believe that a series of events caused the extinctions. Scientists are working for better understand what really happened. I
5、n modern times, we human beings face changing conditions. For humans to live, we need clean air and clean water. Pollution is now a growing problem around the world. Pollution poisons the air and water that we depend on. Polluted air makes people sick and afraid to get outside. Polluted water poison
6、s our food supply. As a result, we never know which foods are safe to eat. Human beings can be not live in a poisoned environment. Therefore, pollution is a major threat to our existence. Humans need temperature to be in a comfortable range. To be in a comfortable range means to be neither too hot n
7、or too cold. With global warming, global temperatures are rising. As global temperatures rise, the polar icecaps will melt. As the polar icecaps melt, ocean levels will rise. Areas of some countries will soon be under water. People would be forced to relocated from flooded areas. In nature, even sma
8、ll changes can sometimes have large effects. Its difficult to predict whats going to happen. The entire ecosystem that we depend on is changing. Some of these changings are irreversible. Irreversible changes cannot be undone. Lets hope the humans are smart enough to understand how the world is chang
9、ing. With more understanding, we make better choices about what to do. We can face the challenge of the pollutions and global warming. We need to do this before its too late. This planet of earth is our only home and we need to protect it. Unit 3-1 vocabularyLizard 蜥蜴Mammals are covered by hair or f
10、ur, have a backbone and warm-blooded. All mammals produce milk for the young. Reptiles are covered by s, includes snakes, lizards and turtles. Reptiles have a backbone and are cold-blooded, which means they often rely on the external resources of heat. Birds are covered by feather and are warm blood
11、ed. Most of the birds can fly and many types of bird migrate great distances. Most insects such ants and bees have a small 3 parts body with 3 pairs of legs. Some insects, such as mosquitoes, spread diseases that cause the deaths of many humans. Unlike animals, plants get the energy that they need f
12、rom the sun. Plants convert light energy along with carbon and water into chemical energy. Scales and rulers are used to measure weight and length. Units of weight includes kilograms and pounds and units of length includes centimeters and inches. These instruments are used to observe very large and
13、very small objects. Telescopes are used by astronomers and microscopes are used by biologists and doctors. These appliances are used in the kitchens of almost every home. Stoves are used to heat food and refrigerators are used to keep foods cool or cold. House tools like these, are used to build or
14、repair things. Hammers are used to pound in the nails and screw drivers are used to turn a screw.Mammals include some of the most intelligent animals on earth, such as elephants and human beings.Mosquitoes cause the death of more human than any other animals. Rulers are used to measure lengthWe can
15、use a telescope to see objects that are far way. Unit 3-1 dialogueDo you know what date is it today?What do you mean, its the special day?Oh, so you dont remember. Remember what? Whats the special?Its our anniversary. We started dating a year ago today. Oh, really. Sorry. Just a minute, what do you
16、think this is. Oh, its a necklace. Do you like it?Yes, I do. Its lovely. Especially the red heart. May I put it on?No, let me do it. So you did remember. Of course I remember. Its very special for both of us. I have something for you too. You do?Yes, but you have to wait until later. Oh, I cant wait. Te
