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课件网) Section A (Grammar Focus) Unit 8 Let’s Communicate! (Period 3) Read and think Find the similarities (相似性) of these sentences. If she has time, she helps her mom with housework. Plants die if they don’t get enough water. If it rains tomorrow, we will stay at home. You will miss the bus if you don’t hurry up. 这些句子都包含 if 从句。 Read the sentences. Find more sentences with if-clauses in Section A. 3a If you want to solve the problem, a face-to-face talk usually works the best. Texting can make things worse if you’re not careful with your words. If the rehearsal ends at 7:00 p.m., I’ll pick you up at 7:15 p.m. If you stay calm and say sorry, it will help. If I go there, I will try all the delicious local food. If you can’t meet, just call your friend. If it is still hard to talk, take a break. If you can come, I’ll be very happy. If you want to make some new friends, this is a good chance. If you talk to ..., I think he / she will be happy to help you. More sentences with if-clauses in Section A: 1. 这些句子在结构上有什么共同特点？由哪些部分组成？ 引导词是什么？主句和从句分别用什么时态或结构？ 2. 这些句子的表意功能是什么？ Let’s learn 零条件句和第一条件句 (Zero and first conditionals) Zero conditionals（零条件句）：指表达客观真理（如科学事实）或习惯性动作的句型。 First conditionals（第一条件句 ）：用于描述将来可能发生的情况。 条件句类型 if从句 主句（谓语动词） 零条件句 If + 一般现在时 一般现在时 第一条件句 If + 一般现在时 will / be going to + 动词原形 零条件句 (Zero conditionals) 1. 结构： If + 一般现在时, 主句 + 一般现在时（或祈使句）. If you mix red and blue, you get purple. 2. 特点：表达永恒真理、科学事实或反复发生的习惯，结果必然发生。 3. 时态：主从句均用一般现在时，强调“必然结果”。 If water freezes, it becomes ice. 适用情况：客观真理 / 习惯性动作 第一条件句 (First conditionals) 1. 结构： If + 一般现在时, 主句 + will + 动词原形（或情态动词 / can / may / should 等）. If it rains tomorrow, we will stay at home. 2. 特点：表达将来可能发生的条件和结果，结果发生的可能性较高。 3. 时态：从句用一般现在时表将来，主句用“will + 动词原形”表将来的动作。 If you study hard, you will pass the exam. He may come if you invite him. 适用情况：将来可能的情况 拓展 1. 第一条件句通常可与以下句型相互转换： (1) 祈使句 + and / or + 一般将来时的句子. eg: If you are quick, you won’t be late for class. =Be quick, and you won’t be late for class. =Be quick, or you will be late for class. (2) 含有介词 with 或 without 的句子 eg: If there is no water, we can’t live. =We can’t live without water. 2. if 从句位置： if 引导的条件状语从句可以放在主句前，也可以放在主句后。 当 if 从句在主句前时，从句后要用逗号与主句隔开；当 if 从句在 主句后时，不用逗号隔开。 If you stay calm and say sorry, it will help. = It will help if you stay calm and say sorry. Match the two parts to make sentences. 3b 1. If we have a face-to-face meeting, 2. If I have good news, 3. If you need to leave, 4. If you can finish yo ... ...
