Period 2: Reading学习目标：1.了解各种自然灾害及其特点2.利用单元词汇自然灾害的危害3.培养快速阅读的能力学习重点：利用单元词汇自然灾害的危害学习难点：良好阅读习惯和阅读能力的培养课前预习使用说明与学法指导：1. 了解背景知识加深对文章的理解2. 15 分钟之内完成教材助读：Four natural disastersA natural disaster is defined as a natural hazard，which has a negative effect on human beings.Though some of the natural disasters are geological，many of them are due to changes in the climatic conditions.Given below are some of the very important natural disasters.Blizzard(暴风雪)A severe winter storm is known as a blizzard.Strong winds，heavy snowfall and low temperatures characterize a blizzard.A blizzard that occurred in 1888 killed over 400 people in the northeastern States.This blizzard is known Great Blizzard of 1888.FloodA flood is a natural disaster as it results in the death of human beings and animals.Crops are destroyed in the flood，which gradually results in increased food prices due to food shortages.In a flood situation，drinking water becomes scarce because water is polluted.Due to this，many diseases can spread.FireFire is terrible especially forest fire.Forest fire is also known as wildfire.It is a natural disaster caused by a volcanic eruption or by human carelessness.Wildfire can threaten wildlife and the human habitation close to the forest.EarthquakeAn earthquake occurs when the tectonic(地壳构造的) plates that form the upper crust of the earth coll ide or slide against each other.When the tectonic plates collide against each other，the stress is released.It is true that animals can sense earthquakes before they occur. However，the behavior of animals cannot be used as a method to predict an occurrence of an earthquake.预习自测：课文原句背诵...
