I left him in a brown study thinking. 我让他好好地想一想。

大家是否还记得福尔摩斯的招牌表情？比如，在他听完扑朔迷离的案件之后会做什么？华生医生是这样形容的：“At that time, Holmes had kept his distance, thinking in a brown study but never leaping to his feet.”“Thinking in a brown study”？ 难道福尔摩斯必须呆在“四壁涂成褐色的书房”里才能完成缜密推理吗？
其实，“in a brown study”是个固定搭配，指“in a state of deep thought”，即“沉思”的意思。