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1、高二英语Unit10 Frightening nature一. 本周教学内容：Unit 10 Frightening nature二. 教学目标：1. Master some phrases and sentence patterns2. Talk about natural disasters: volcanoes and typhoons3. Write a creative writing三. 教学重点与难点： Learn about Ellipsis四. 具体内容：Background informationVolcanoesThere are thousands of volcano
2、es all over the world. What makes volcanoes? What happens?The inside of the earth is very hot. Because it is very, very hot, the rock has melted like ice. It has become liquid, like water. It is always boiling, like water in a kettle. If you have seen a kettle boiling, you know that the steam and bo
3、iling water try to get out. The very hot melted rock inside the earth also tries to get out. Usually it cannot because the outside of the earth is too thick and strong.But in some places the outside of the earth is thin and weak. Sometimes a crack appears. The hot melted rock, which we call “ lava ”
4、, pushes up through the crack and bursts through. Steam and gas shoot up into the air and the hot melted lava pours out. Big pieces of rock may be thrown high into the air.After a while the volcano becomes quiet again. The melted lava becomes hard. Later the same thing happens again and again. Each
5、time more hot lava pours out on top of the cold lava and then becomes hard. In this way a kind of mountain is built up, with a hole down the middle . Perhaps the volcano will then be quiet and no more lava will burst out. Perhaps it will start again hundreds of years later.Although there are thousan
6、ds of volcanoes in the world, most of them are dead. Only about 500 sometimes start to throw out lava again. A famous volcano which is now dead is Mount Fujiyama in Japan. It is covered with snow in winter.Vesuvius is the name of a very famous volcano in Italy. It first came to life many, many years
7、 ago. It was quiet for hundreds of years. Then in the year 79 it suddenly burst. A great cloud of smoke shot up into the sky with great burning rocks, which fell all around. Hot lava poured down its sides. About 3000 people were killed.This has happened again many times since that year. Sometimes no
8、 damage was caused, or only little damage. But there was serious damage in the years 472, 1631, 1794, 1861, 1872 and 1906. You can see that a volcano can stay alive for many years. In 1906 part of the top of the mountain fell off. There was also serious damage in 1914 but there has not been any sinc
9、e last year.Fire and smoke coming from the top of the mountain have always made people curious about the source of that fire and what the interior of the earth might look like. The power, heat and bright red and orange colors of melten rock are as fascinating as ever. Many accidents have happened to
10、 people who are drawn too close to observe this maginificent spectacle.People have always known volcanoes to be dangerous. Nonetheless, we find human communities and villages built at the foot of many volcanoes everywhere around the world. This is because the earth around volcanoes is very fertile,
11、so farmers were always attracted to plant their crops near these mountains. Also, the fact that some volcanoes have long periods of time without being active, has often given people a sense of security. Some volcanoes that had been inactive for many generations and were thought to be dead, suddenly
12、sprang back to life and killed thousands of people.TornadoThe phenomenon usually occurs on a hot, sticky day with south winds and an ominous sky. From the base of a thunderhead, a funnel-shaped cloud extends a violently twisting spout toward the earth. As it sucks in matter in its path, the twister
13、may turn black, brown, or occasionally even white. The moving cloud shows an almost continuous display of sheet lightening. It lurches along in a meandering path, usually northeastward, at 25 to 40 miles per hour. Sometimes it picks up its finger from the earth for a short distance and then plants i
14、t down again. The funnel is very slender, its wake of violence averages about 400 yards wide. As the tornado approaches, it is heralded by a roar as of hundreds of jet planes or thousands of railroad cars. Its path is a path of total destruction. Buildings literally exploded as they are sucked in by
15、 the tornados low-pressure vortex and by its powerful whirling winds. The tornados lifetime is as brief as it is violent. Within a few tens of miles, it spends its force and suddenly appears.EarthquakesEarthquake is a sudden, violent shaking of the earths surface. Its a kind of crustal movement form
16、 of expression.Earthquake is regarded as one of the most damaging forces known to man: since records began to be written down, it has been estimated that earthquake-related fatalities have been numbered in the millions, and that earthquake-related destruction has been beyond count.The great majority of all earthquakes occur in two specific geographic areas. One such area surrounds the Pacific Ocean and its contiguous land masses.
