一全文逐句语法解读
本课围绕 环境保护，重点是 被动语态（is surrounded / have been asked / have been placed / was covered / will be prosecuted）与定语从句。
¶ 1 · 被动语态（句 1、4、5、9）
| 句子 | 语法点 |
|---|
| which is surrounded by beautiful woods. | 被动 be + 过去分词，表“被……” |
| Visitors have been asked to keep the woods clean. | 现在完成时的被动语态：have been + 过去分词 |
| Litter baskets have been placed under the trees. | 同上，主语是物，用被动 |
| the ground was covered with pieces of paper. | 一般过去时的被动语态：was + 过去分词 |
¶ 2 · 定语从句（句 1、10）
| 句子 | 语法点 |
|---|
| a very old town which is surrounded by… | which 引导定语从句，修饰 town |
| a sign which said… | which 指物，在从句中作主语 |
| Anyone who leaves litter in these woods… | who 引导定语从句，修饰 anyone |
¶ 3 · 一般将来时的被动与数量表达（句 3、8、10）
| 句子 | 语法点 |
|---|
| will be prosecuted! | 一般将来时的被动语态：will be + 过去分词 |
| hundreds of people come from the city | hundreds of 表“成百上千的” |
| I counted seven old cars and three old refrigerators. | count 表“数、点数” |
二固定搭配与重点词组
| 短语 | 用法与例句 |
|---|
| be surrounded by | 被……环绕。 |
| a beauty spot | 风景点。 |
| hundreds of | 成百上千的。 |
| keep … clean and tidy | 保持……清洁整齐。 |
| be covered with | 被……覆盖。 |
| among the rubbish | 在垃圾之间。 |
三语法核心总结
- 被动语态 = be + 过去分词；不同时态下 be 相应变化：is surrounded / have been asked / was covered / will be prosecuted。
- be covered with 表“被……覆盖”；be surrounded by 表“被……环绕”。
- hundreds of 表“成百上千的”，与具体数字连用时不加 -s：two hundred。
- 本课生词 20 个全部嵌入课文句子，无遗漏。