Unit 4 Space Exploration Period 3 Discovering Useful Structures（47张PPT）-32762435

Unit 4 Space Exploration Period 3 Discovering Useful Structures 人教版本 必修三 * Lead-in What Powers a Spacecraft? Spacecraft have instruments to help them take pictures and collect information in space. But they need electricity to power those instruments and send the information back to Earth. Where does the power come from? Lead-in What Powers a Spacecraft? A spacecraft generally gets its energy from at least one of three power sources: the Sun, batteries or unstable atoms. To choose the best type of power for a spacecraft, engineers consider where it is traveling, what it plans to do there and how long it will need to work. Lead-in How many “to” in the text? Do you know their meanings and functions? New words They charged the accident to the lack of experience. Please call before you come, otherwise we might not be home. or else differently in other ways not have sth. not have enough of sth. New words It goes beyond our research. These materials can be recycled into other packaging products. Current success does not mean success in the future. save for reuse use again differently reuse sth. past except impossible for existing now valid flow of water or air New words We have provided sufficient information to you on this issue. Let them figure out the answer without you. enough work sth. out decide Let’s play 看谁答的快又准！ Let’s play 1. Be modest, _________ you will lag behind. 2. _______ of food and supplies caused disaffection among the soldiers. 3. They _________ empty tins so as to use the metal. 4. The contents go far _______ the title. 5. Even though they are a step in the right direction, our_______ processes are not enough. 6. They had no evidence _________ to hold him. 7. Father is trying to figure ______ his tax. otherwise Lack recycle beyond current sufficient out Let’s learn Look at the following sentences and focus on the italicized infinitives. In pairs, discuss their functions and meanings. I trained for a long time to