Unit 4 Amazing ScienceUnit 4 Amazing Science Topic 2 Topic 2 When was it invented?When was it invented?Have you ever got lost somewhere? What method did you use to find your direction? Read and discuss the following questions.1. What would you do if you lose your way in a forest?2. How did the early explorers know where they were?3. What is GPS? Is it useful to us?4. What do you think GPS will be used for in the future? What is GPS?GPS 即全球定位系统 (Global Positioning System) ，简单地说，这是一个由覆盖全球的 24 颗卫星组成的卫星系统。这个系统可以保证在任意时刻，地球上任意一点都可以同时观测到 4 颗卫星，该观测点可以通过接收到的信号计算出经纬度和高度，以便实现导航、定位、授时等功能。这项技术可以用来引导飞机、船舶、车辆以及个人，安全、准确地沿着选定的路线，准时到达目的地。 疑难讲解1.in …direction 按 / 朝……方向e.g. A motor bike hit a truck in the opposite direction.2. work well 奏效；起作用e.g. The medicine worked well.3. as long as 只要；长达e.g. You can go out to play as long as you finish your homework.e.g.I have taught English as long as nine years.Read and answer the question. A thief stole a beautiful cellphone from a young girl. He ran away very quickly and then hid in a secret place. To his surprise, when he was using the cellphone, he was caught by the police. Do you know why Bluetooth Bluetooth is a short distance wireless communication technology. It provides coverage ( 覆盖） of up to 100 meters. It’s a low power technology that can be used to connect cellphones or computer with other devices.A bluetooth headset长长见识根据首字母提示，完成短文。 Thanks to GPS, we can exactly know w _____we are now. GPS is like a man-made “star”. It can be u____ in any place and any weather condition to find out our p_...
