设计任务：请阅读下面学生信息和语言素材，设计一个25分钟的听力教学活动 。　　教案没有固定格式，但须包含下列要点：　　● teaching objectives　　● teaching contents　　● key and difficult points　　● major steps and time allocation　　● activities and justifications　　教学时间：25分钟　　学生概况：某城镇普通中学高中一年级学生，班级人数40人 。多数学生已经达到《普通高中英语课程标准(实验)》五级水平 。学生课堂参与积极性一般 。　　语言素材：　　Why do earthquakes happen? Scientists explain that the outside of the earth is made of a number of different plates . At San Francisco, the Pacific plate which is moving towards the northwest meets the North American plate . The Pacific plate is moving very slowly-at 5 .3 centimeters a year . Sometimes these two plates stop and do not move for years . Then suddenly, they jump and an earthquake is felt . As a result of the movement of these plates, California has always had a lot of earthquakes . When the 1906 earthquake happened, the Pacific plate jumped 5-6 meters to the north .　　China also has an unlucky place on the earth . The Pacific plate is also pushing on China from the east as the plate moves west . Likewise, the Indian plate is pushing on China from the southwest as that plate moves northeast . The same power that produced the great Himalayan Mountains now causes earthquakes in China .　　We cannot stop earthquakes, but we can do things to make sure they do not destroy whole cities . First, it is not a good idea to build houses along the lines where two of the earth's plates join together . Second, if you think there may be an earthquake, it is better to build houses on rock than on sand . Third, you must make the houses as strong as possible . Weak buildings will fall down in an earthquake, but strong ones may stay up .