应该是时间状语.
进行如下的改写后分析就可以得出结论:
1、如果是原因状语.分词短语可以改写为用 because 引导的状语从句:
My son had hurt himself because he played football.
——注意:主句是过去完成时,说明受伤在前,踢足球在后,意思是“ 因为踢足球,我的儿子在这之前受伤了”.不可能构成因果关系,说明原因状语不合逻辑.如果把过去完成时改为一般过去时,即 My son hurt himself because he played football 就合情合理了.
2、如果是伴随状语,分词短语可以并列分句:
My son had hurt himself and he was playing football.
——意思是“我的儿子在前已经受伤了,于此同时他在踢足球”.受伤与踢足球时间段不一致,踢足球显然不能是受伤的伴随动作,因此也不符合逻辑.
3、 如果是时间状语,分词短语可以改写为用 when 引导的从句:
My son had hurt himself when he played football.
——意思是“我儿子在踢足球的时候已经受伤了”.说明带着伤踢足球,合乎逻辑.