这个单元有 5 章：主题课文"我们学校的塑料战争"、词汇延展（自然/环境/污染词族）、语法延展（if 条件句第一类 + 第二类入门）、功能句型（谈环保、写 Email）、PET 考点与自测。
学完你能：用 80+ 自然与环保词聊"气候/回收/污染"；分清 if 第一类（真实可能）和第二类（虚拟假设）；在 PET 写作 Part 1 Email 里写一封"呼吁同学减少塑料"的 100 词短信；口语 Part 4 回答"我们能为地球做什么"。
预计时间：1 周。
衔接说明：条件句是 B1 语法的"半壁江山"——第一条件句（If + 现在时, will...）和 U5 的 will 直接打通；第二条件句（If + 过去时, would...）是 FCE 重点，这里先打个底。
Natural World & Environment = 自然/污染/回收词族 + if 第一类/第二类 + 环保呼吁句型。课文带你看 16 岁的 Leo 在学校发起"减塑"运动，词汇按"自然景观/环境问题/环保行动"分组，语法把"如果…就会…"讲透。
主题课文 · 我们学校的塑料战争
课文 · What If We Just Stopped Buying Plastic?
课文精讲 · B1 版"环保呼吁"四步
论从"我们要环保"到"如果大家这样做会怎样"
KET 版：Don't use plastic. Recycle. Save the planet.——口号三连，没有逻辑。
PET 版：① 摆事实（if we continue..., there will be...）；② 提假设（if everyone used..., we would save...）；③ 定行动（If we reach 300 names, we will present...）；④ 驳反对（if everyone thought like that, nothing would ever change）。
考试怎么考：PET 写作 Email "write to a friend about an environmental project"，口语 Part 4 "What can we do to protect the environment?"。四步走完，if 第一类和第二类各踩一个，考官一眼看到语法层次。
① single-use plastic 一次性塑料
② reusable bottle / bag 可重复使用的瓶子/袋子
③ collect signatures 收集签名
④ ban plastic 禁用塑料（ban + 名词）
⑤ recycle / recycling 回收（动词/名词）
词汇延展 · 自然、污染与环保行动词族
四组词族 · 自然、问题、行动、态度
（可参看「环境词族」深化页）| 组 | 核心词 | 搭配/备注 |
|---|---|---|
| 自然景观 | mountain, river, ocean, sea, forest, jungle, desert, island, beach, lake, field, valley, wildlife, animal, plant, tree, flower | ocean 比 sea 更"大洋" |
| 环境问题 | pollution, plastic, waste, rubbish, litter, climate change, global warming, greenhouse effect, flood, drought, deforestation, endangered species, extinction, carbon footprint | pollution 不可数 |
| 环保行动 | recycle, reuse, reduce, save energy, turn off lights, use public transport, plant trees, go green, eco-friendly, renewable energy, solar power, wind power | 3R: reduce, reuse, recycle |
| 态度与形容 | important, necessary, worried, hopeful, guilty, responsible, serious, urgent, avoidable, endless, beautiful, awful | be worried about / be responsible for |
① pollution vs pollutant：pollution = 污染（总称，不可数）；pollutant = 污染物（具体物质，可数）。PET 常用 pollution。
② rubbish vs garbage vs trash：英式 rubbish；美式 garbage/trash。PET 以英式为主。
③ recycle vs recycling：recycle 动词（I recycle）；recycling 名词（a recycling club）。别混。
④ endangered vs dangerous：endangered = 濒危（物种）；dangerous = 危险的（对人危险）。pandas are endangered。
语法延展 · if 条件句第一类与第二类
第一类 vs 第二类对照表
（可参看「条件句一二类」深化页）| 类型 | 结构与含义 | 例子 |
|---|---|---|
| 第一类（真实） | If + 现在时, will + 原形。可能发生、真有可能。 | If we reach 300 names, we will present it. |
| 第二类（虚拟） | If + 过去时, would + 原形。与现在事实相反/不太可能。 | If everyone used a bottle, we would save thousands. |
| 第二类 be 动词 | 所有人称多用 were（口语可用 was） | If I were you, I would talk to the teacher. |
| 否定 | If + not, won't / wouldn't + 原形 | If it doesn't rain, we will go out. |
| 疑问 | What would you do if...? | What would you do if you saw a bear? |
① 第一类不能用 will：❌ If we will reach 300 names, we will present it. ✅ If we reach 300 names, we will present it.（if 从句用现在时表将来）
② 第二类不能用 will：❌ If everyone uses a bottle, we would save. ✅ If everyone used a bottle, we would save.
③ were 与 was：If I were you（虚拟建议，标准）；口语里 If I was you 也常见，PET 写作推荐 were。
④ 逗号：If 从句在前，主句后加逗号；主句在前，不加逗号。We will go out if it doesn't rain.
⑤ 考试怎么考：PET 阅读 Part 5 完形最爱挖 if 从句动词时态。判断：真有可能→现在时；虚拟/不太可能→过去时。
第二条件句的两个"实战场景"
| 场景 | 例子 |
|---|---|
| 给虚拟建议 | If I were you, I would use a reusable bottle. |
| 谈不太可能的想象 | If I won a million pounds, I would buy a forest. |
| 礼貌请求/委婉 | I would like a coffee, please.（与 if 无关，但 would 同源） |
情景操练
即学即用
练习1（第一/第二类）：① If it ___ (rain) tomorrow, we ___ (stay) home. ② If I ___ (be) the head teacher, I ___ (ban) single-use plastic. ③ If everyone ___ (recycle), the world ___ (be) cleaner. ④ What ___ you ___ (do) if you ___ (find) a wallet on the street?
练习2（改错）：① If it will rain, we won't go. ② If I would have more time, I would help. ③ If I were you, I will tell the teacher.
练习3（合并句子）：We will plant more trees. Then the air will be cleaner. → If we ___, ___.
练习4（写自己的话）：写一句真实可能（If I..., I will...）和一句虚拟假设（If I..., I would...）。
查看参考答案
- 练习1：① rains / will stay（第一类，明天真可能下雨） ② were / would ban（第二类，虚拟） ③ recycles / would be（第二类） ④ would / do / found（第二类疑问）
- 练习2：① If it rains, we won't go（if 从句用现在时） ② If I had more time, I would help（第二类 if 用过去时） ③ If I were you, I would tell the teacher.
- 练习3：If we plant more trees, the air will be cleaner.
- 练习4（示范）：If I finish my homework early, I will go for a walk. If I had a garden, I would plant fifty trees.
功能句型 · 谈环保与写呼吁 Email
三套句型模板
If we continue like this, sea levels will rise.
There will be more plastic than fish by 2050.
Climate change is getting worse every year.
We should use reusable bottles.
If everyone did this, we would save thousands.
Why don't we start a recycling club?
Some people say one school can't change the world.
But if everyone thought like that, nothing would change.
Small steps, but they matter.
场景对话 · 校长与学生代表
Leo: We want to ban single-use plastic in the canteen. If we do that, we will save thousands of bottles a month.
Head teacher: But some parents will complain. They say children need water.
Sophie: If every student brings a reusable bottle, they won't need to buy plastic ones.
Head teacher: It sounds expensive to change.
Leo: If I were you, I would try it for one term. If it doesn't work, we can go back.
Head teacher: That is a fair point. Leave the petition with me, and I will discuss it with the staff.
Email 骨架 · 呼吁同学减塑
论100 词 Email 三段式（呼吁类）
开头（20 词）：Hi Tom, you know that video about ocean plastic? It really shocked me, so I've started a project at school.（背景 + 动作）
中间（60 词）：三条——① If we ban plastic..., we will save...；② If everyone brought..., we wouldn't need...；③ We should also...。第一类 + 第二类 + should 各一句。
结尾（20 词）：Can you help us collect signatures? If you're interested, write back! Best, Leo.
考试怎么考：PET 写作 Part 1 呼吁类 Email 常考；if 第一类和第二类各踩一个，就是考官要的"语法多样"。
PET 考点 · Natural World & Environment 怎么考 + 自测
考点分布表
| 卷子/题型 | 题型示例 | 应对策略 |
|---|---|---|
| Reading Part 3 | 人物与环保主张配对 | 抓 if / should / 环保动词 |
| Reading Part 5 | 完形：if 从句时态、环保词 | 判断真实/虚拟选时态 |
| Writing Part 1 | Email 100 词：环保项目/呼吁 | 第一类 + 第二类 + should |
| Listening Part 2 | 听对话填环保行动信息 | 抓 recycle / reduce / reusable |
| Speaking Part 4 | 讨论"我们能为地球做什么" | If everyone..., we would... 表态 |
本单元自测 · 8 题
PET Natural World 自测
1（填空）：If we ___ (not/reduce) plastic, the oceans ___ (suffer).（第一类）
2（选择）：If I ___ the head teacher, I would ban single-use plastic. A. am B. were C. will be
3（易混）：Pandas are ___ species. A. dangerous B. endangered C. polluted
4（改错）：If it will be sunny tomorrow, we will have a picnic.
5（阅读判断）："If everyone thought like that, nothing would ever change." —— Sophie thinks small schools can change the world. A. Right B. Wrong C. Doesn't say
6（听力）：听到 "We should recycle paper, and if we recycled more, we would cut fewer trees." —— 说话人用了哪两类条件句？
7（写作）：用第一类条件句写一句"如果学校禁用塑料会怎样"。
8（口语）：用三句话回答：What can young people do to protect the environment?
查看参考答案
- 1：If we don't reduce plastic, the oceans will suffer.
- 2：B（第二类 be 动词用 were）
- 3：B（endangered = 濒危）
- 4：If it is sunny tomorrow, we will have a picnic（if 从句用现在时）
- 5：A（她反对"小学校改变不了世界"，即她认为能改变）
- 6：前半句 should recycle（建议）；后半句 If we recycled..., we would cut...（第二类虚拟）
- 7（示范）：If our school banned single-use plastic, we would save thousands of bottles a month.
- 8（示范）：Young people should use reusable bottles. If everyone recycled paper, fewer trees would be cut. We can also take public transport to reduce pollution.
PET 收官前路线图
论U7 之后，PET 只剩最后一座山
语法升级：条件句拿下后，U8 进被动语态——情态动词 + 被动（must be done / should be done）会把 U6 和 U8 串成一张网。这是 PET B1 的最后一块语法拼图。
词汇升级：最后一块话题是"科技与通讯"——手机、邮件、社交媒体、AI，这也是口语 Part 4 最高频话题。
考试升级：U8 学完，PET 四模块（Reading/Writing/Listening/Speaking）的题型就全部覆盖了。接下来就是成套真题模拟 + 限时训练。
现在就做：把 if 第一/第二类练到条件反射，下一站是 PET Unit 8（Technology & Communication）——PET 收官单元，学完直接通向 FCE。
在线学习资源 · 剑桥官方
- 剑桥 Preliminary (PET) 官方考试页（内含免费样题/真题下载）
- Cambridge English 免费学习资源
点进官方考试页可下载免费样题；本课程课文为同主题原创内容，知识点与官方大纲对齐。