语法总结
被动语态贯穿全文
is called, was made, is kept, was bought, was damaged, were broken 这些都把焦点放在 clavichord 本身，而不是执行动作的人。
相似句：
- The book was written in French.
- The windows were broken in the storm.
现在进行时的被动语态
It is being repaired 表示“现在正在被修理”，结构是 am/is/are + being + 过去分词。
相似句：
- The road is being repaired now.
- The house is being painted this week.
allow 的主动与被动转换
allow sb. to do sth. 变成被动就是 sb. be allowed to do sth.；本课里 we are not allowed to touch it 正是这个结构。
相似句：
- They don't allow visitors to take photos.
- Visitors are not allowed to take photos.
a friend of my father's 双重属格
这不是“我父亲唯一的朋友”，而是“我父亲众多朋友中的一位”，双重属格常带“其中之一”的意味。
相似句：
- He is a classmate of mine.
- She borrowed a book of her brother's.