语法点：被动语态 (Passive Voice)
当我们更关心"动作的承受者"而不是"谁做的"时，就用被动语态。本课讲一件古钢琴，它被制造、被保存、被购买、被损坏、正在被修理——主语始终是这件乐器，所以全文大量使用被动语态。被动语态的核心是 be + 过去分词，be 的形式随时态变化：一般现在时 is kept，一般过去时 was made，现在进行时 is being repaired。如果需要说明动作的执行者，用 by 引出。
结构
| 时态 | 结构 | 课文例句 |
|---|---|---|
| 一般现在时 | am / is / are + 过去分词 | It is called a clavichord. |
| 一般过去时 | was / were + 过去分词 | It was made in Germany in 1681. |
| 现在进行时 | is / are + being + 过去分词 | It is being repaired by a friend. |
| 否定 | be + not + 过去分词 | We are not allowed to touch it. |
| 疑问 | Be + 主语 + 过去分词? | Was it made in Germany? |
主动变被动三步：宾语提前作主语 → 动词变 be + 过去分词 → 原主语放到 by 后面（可省略）。
课文中的例句
- [句 2] It is called a clavichord. — 一般现在时被动，执行者不重要，省略 by
- [句 3] It was made in Germany in 1681. — 一般过去时被动，有明确过去时间
- [句 4] Our clavichord is kept in the living room. — 一般现在时被动表示现状
- [句 6] The instrument was bought by my grandfather many years ago. — by 引出动作执行者
- [句 11] Now we are not allowed to touch it. — 被动语态的否定形式
- [句 12] It is being repaired by a friend of my father's. — 现在进行时被动：is being + 过去分词
补充例句
- The keys were struck too hard. 琴键被敲得太重了。
- Two strings are being repaired now. 两根弦现在正在修理。
- Was the instrument damaged by a visitor? 这件乐器是被一个客人弄坏的吗？
易错点
- ❌ It was make in Germany. → ✅ It was made in Germany. 被动语态必须用过去分词，不是动词原形。
- ❌ It is repairing by a friend. → ✅ It is being repaired by a friend. 现在进行时的被动要用 is being + 过去分词。
- ❌ Two of the strings was broken. → ✅ Two of the strings were broken. be 动词要和主语 strings（复数）一致。
- ❌ The instrument bought by my grandfather. → ✅ The instrument was bought by my grandfather. 被动语态不能省略 be 动词。