[正]in the room [誤]at the room

・"room"に対する場所を示す前置詞は"in"を使う。
・"at"を使うのは、立ち寄った一点としてイメージされる場合に限られる。

[正] Mary is writing the diary in her room.
[誤] Mary is writing the diary at her room.
[正] She is in the living room.
[誤] She is at the living room.

[正] On her way to the gym, she stopped at Professor Jones' room.

[正]in the room [誤]at the roomの関連項目