Unit 4 Amazing Science Welcome to the unit Topic 2 When was it invented? Section D New words landmark 地标，里程碑地标，里程碑 global 全球的，世界的全球的，世界的 thief 小偷小偷 run away 逃跑，失控逃跑，失控 Teaching aims and demands 1. Learn new phrases and useful expressions: as long as, run away, in short In short, this robot is very useful to us. 2. Sum up the simple past passive voice. 3. Talk about new technologies and inventions. Look and discuss. Whats this? What can we use it to do? 1. What is GPS? Is it useful to us? Its li
