She's always been interested in keeping fit.为什么句中要用been
问题描述：
She's always been interested in keeping fit.为什么句中要用been
答
be interested in对.感兴趣
整个句子的时态是现在完成时,构成形式：主语+ have / has +动词的过去分词,she's= sha has ,be 的过去分词是been