Unit 4 Section Ⅰ 人教版英语必修一同步课件 (共39张PPT)

Unit 4 Earthquakes [话 题 导 读] 地震危害性很大，地震是如何发生的呢？地震来临时，我们应该如何做呢？ Earthquakes How does an earthquake start? What makes an earthquake happen？The rock of the earth's crust (地壳) may have a “fault”(责任)，a kind of break in the surface.The blocks which make up the earth move，and sometimes this may cause the sides of the crust to move up and down or lengthways (纵向地)against each other.When one piece of rock starts to rub on another with great force，a lot of energy is used.This energy is changed into vibrations (振动)and it is these vibrations that we feel as an earthquake.The vibrations can travel thousands of kilometers and so an earthquake in Turkey may be felt in Greece. What to do during an earthquake? At school As soon as the earthquake starts，students should get under the desks immediately and wait until the teacher tells them it is safe to come out.The teacher should，at the same time，go immediately to the teacher's desk，get underneath (在……下面)it and stay there till the danger is over.Students