There is no swimming-pool in this school and the students often go to swim . A. indoors;

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A. indoors; outdoors
B. indoor; outdoor
(答案→)C. indoor; outdoors
D. indoor; indoors
解析：词性辨别。Indoors adv室内地；在室内。Indoor adj室内的。第一空用indoor做定语修饰swimming-poor.第二空用副词indoors做状语修饰go to swim.故C正确。