语法总结
must have been 表过去推测
It must have been about two... 说明作者对过去时间做有把握推测。
相似句：
- He must have been tired after the trip.
- It must have been raining at that time.
by doing 表方式
by ringing the doorbell 说明他尝试叫醒妻子的方式。
相似句：
- She solved the problem by asking for help.
- He opened it by pushing the handle.
would you mind ...
警察用礼貌形式包裹正式要求，使对话更有英式幽默味道。
相似句：
- Would you mind waiting a moment?
- Would you mind coming with us?