UNIT 3 SEA EXPLORATION（Word教参）-【优化指导】2021-2022学年新教材高中英语选择性必修第四册(人教版2019)

海洋是生命的摇篮，所有生命的祖先都诞生在海洋之中。地球表面70%是海洋，从海面到几千米深的海底，生活着并不为我们所熟悉的各种生物。庞大的鲸鱼、聪明的海豚、凶猛的鲨鱼、彩色的珊瑚鱼、阴险的大乌贼、灵巧的企鹅。海洋对人类的意义重大，目前为止，人类已探索的海底只有5%，还有95%大海的海底是未知的。 What do you know about the sea？We know that it looks very pretty when the sun is shining on it.We also know that it can be very rough① when there is a strong wind.What other things do we know about it？ The first thing to remember is that the sea is very big.When you look at the map of the world you will find there is more water than land.The sea covers②three quarters of the world. The sea is also very deep in some places.It is not deep everywhere.Some parts of the sea are very shallow③.But in some places the depth of the sea is very great.There is one spot，near Japan，where the sea is nearly 11 kilometres deep！The highest mountain in the world is about 9 kilometres high.If that mountain were put into the sea at that place，there would be 2 kilometres of water above it！What a deep place！ If you have swum in the sea，you know that it is salty.You can taste the salt.Rivers，which flow into the sea，carry salt from the land into the sea.Some parts of the sea are saltier than other parts.There is one sea，called the Dead Sea，which is very salty.It is so salty that swimmers cannot sink！Fish cannot live in the Dead Sea！ In most parts of the sea，there are plenty of fishes and plants.Some live near the top of the sea.Others live deep down.There are also millions of tiny living things that float in the sea.These floating things are so small that it is hard to see them.Many fish live by eating these. The sea can be very cold.Divers who go deep down in the sea know this.On the top the water may be warm.When the diver goes downwards，the sea becomes colder and colder.Another thing happens. When the diver goes deeper，the water above presses down on④ him.It squeezes⑤ him.Then the diver has to wear clothes made of metal.But he cannot go very deep.Some people who wanted to go very deep used a very strong diving ship！They went down to the deep