第21题: [单项选择]Its skin color follows a regular twenty-four hours cycle that exactly matches the daily ______ of the sun. A. rotation B. variance C. rhythm D. motion 参考答案:C 答案解析:[解析] 语义连贯题。rhythm和cycle形成语义场共现。[C]rhythm除了有“节奏”之意外,还可意为“有规则的变化;有规则的循环运动”,如the rhythm of the seasons(