单选题 Sometimes the messages are conveyed through deliberate "conscious gestures", other times, our bodies talk without our even knowing it.
【正确答案】 D
【答案解析】[解析] 题干：约翰不相信常规的药品，他有着自己的治疗方法。四个选项的意思为：standard标准的；regular通常的；routine日常的；conventional常规的。故答案为D。