语法总结
过去完成时 + 一般过去时
本课里先发生的是床已经撞地，后发生的是人醒来，所以用 had + 过去分词 来交代“先发生的过去动作”，再用一般过去时写后续动作。
相似句：
- The bed had struck the ground before the young man woke up.
- After he had put the mattress on the floor, he went to sleep again.
not ... until ...
本课原句 The young man did not wake up until ... 用来表达“直到……才……”，适合写动作延后发生，突出前面那件事先完成。
相似句：
- He didn't wake up until the storm became stronger.
- The child didn't cry until his mother left the room.
分词 / 形容词短语作状语
开头的 Tired of sleeping on the floor 和后面的 Glancing at the bits of wood and metal 都不是完整谓语，而是用来补充人物状态或伴随动作，和主语保持逻辑一致。
相似句：
- Tired after the long walk, he lay down on the bed at once.
- Looking round the room, she found her bag on the floor.
定语从句贴着名词补充信息
课文里 a bed which had springs and a mattress、the bits of wood and metal that lay around him 都是在名词后面补充说明，帮助把对象说具体。
相似句：
- He bought a house which stood on a hill.
- She picked up the books that were lying under the desk.