题目内容：

when it is,I usually go swimming.填rain的形式
麻烦帮我讲一下为何要这样填?

优质解答

虽然考题可能要你填 raining ,但我觉得 填 not raining 比较符合逻辑.when it is (not raining),I usually go swimming.不下雨时我通常去游泳.when it is ...要跟动词+ing 作为现在进行时,when it is not ...也一样....