Unit 2 Discover useful structures 课件-2022-2023学年高中英语人教版（2019）选择性必修第三册

Period 3 Discovering useful structures The infinitive of the verb used as the subject Unit 2 Healthy Lifestyle 1 单元语法自我探究 Look at the following sentences and pay attention to the italicized infinitives. Find more infinitives in the reading passage, and tell their meanings and functions. 1. To change bad habits is never easy. 2. It took the surgeon three hours to finish my mother’s lung surgery. 3.To join the people’s Liberation Army, it is required for men to shave off their beards. 4. It was not polite to disturb your neighbors with loud music last night. 主语 主语 主语 目的状语 动词不定式作主语时，谓语动词用单数。 To look after these naughty boys is really difficult. To get up early is necessary. To learn a skill is important for everyone in society. To change bad habits is never easy. It作形式主语，动词不定式作真正的主语放在句末。 It took the surgeon three hours to finish my mother’s lung surgery. 基本用法 Observe Observe and Discover 1. It isn’t right to talk like that. 2. It’s difficult to master English. 3. It’s hard for me to answer the question. 4. It is important to learn a useful skill. Discover 1.以上句子的真正主语都是____________，但都使用it作形式主语； 2.以上句子的表语都是______。 动词不定式 形容词 Find more infinitives in the reading text. 1….it can be easy for some of them to form bad habits. 2. After all, it is not easy to break bad habits. 3. ... ... 动词不定式在句中做主语，有时为了保持句子的平衡，避免头重脚轻，常用it做形式主语，而真正的主语放在句子末尾。 Their meanings and functions Find and Discover Group Work 语法研析 不定式作主语，it 做形式主语的常见结构： 1. It is +adj.+(for sb) to do It is easy for me to learn how to drive. 2. It is +adj.+(of sb) to do It is clever of you to apply for the position. 3. It is +n.+ to do sth( an honour, our duty, a pity, a shame) It is our duty to take care of you. 4. It takes/took sb some time to do sth. It takes me half an hour to do my housework. It is +adj.+(of sb) to do 1. 对我来说每天读英语是很重要的。 2. 你真是太好了，能帮我学英语。 3. 能帮助你是我的荣幸。 4. 我每天花15分钟读英语。 Translation It is very kind of you to help me learn English. It is +adj.+(for sb) to do It is +n.+ to do sth( hon