a lavatory seat的用法和样例：
- Do not use this place as a lavatory.
- The room is converted from a kitchen to a lavatory.
- There's a bathroom and a lavatory upstairs.
- Half way up the stairs there was a lavatory ... "The House of Lords, " said Jake.
楼梯中间有个厕所 ... “人家管它叫‘上议院’