暑假期间，他在游泳场周围插上竹竿，拉上绳子，组织20多名男女学生练习游泳。
B-Time I-Time I-Time I-Time O B-Person O O O O B-Location I-Location B-Thing I-Thing I-Thing I-Thing O O O B-Thing I-Thing O O O B-Metric I-Metric I-Metric I-Metric B-Person I-Person I-Person I-Person O O O O O