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Suggested answers: 1.Tides provide energy for the ecosystem,and estuaries are protected from waves and storms by islands.In addition nutrients arrive in estuaries from both the land and the ocean.So estuaries are great places for nature’s young ones. 2.Density means the quality of being dense.In other words,there are more living creatures than any other habitat on earth. 3.Estuaries can make our water clean by absorbing nutrients and pollutants from water coming from inland sources. 4.The function that estuaries can absorb pollutants and nutrients makes estuaries very sensitive to environmental pollution. 5.Estuaries can provide recreation and education for human beings.Besides estuaries also contribute to the economy.So they are very important to human beings. T:Well done.Now you are very familiar with the passage. To understand the passage better,I will explain some important phrases.Please,look at the blackboard. (Teacher writes the following phrases on the blackboard.) 1.provide…for e.g.The company will provide food and drink for them. 2.have an opportunity to do something e.g.I had no opportunity to discuss the problem with her yesterday. 3.a variety of e.g.He left for a variety of reasons. There are a variety of patterns for you to choose from. 4.contribute to e.g.His work has contributed to our understanding of this difficult subject. CStep Ⅴ Writing T:Up to now,we have learnt a lot about water and known the properties of water and importance of estuaries.Now you are given an opportunity to check if you know a lot about water.Look at the questions on the screen. (Teacher uses multimedia to show the questions on the screen.) 1.Why does an ice cube float? 2.What will happen to a piece of metal if you put it in water? 3.Why do so many species live in estuaries? 4.Why have so many cities been built by estuaries? T:Now imagine that your science teacher asks you to choose one of the questions and write a paragraph to explain it.Use what you learn from this unit and what you know about nature and science to write the paragraph.You must be careful to explain it to make your explanations easy to understand.You’d better look at the tips on Page 24 before you write.It’s of great help to your writing. (责任编辑：admin) |