短语词组短语double envelopment 两面包围;双面包抄envelopment tendency 发展趋势date envelopment 数据包络Envelopment u 环绕感listening envelopment 听包被感envelopment rate 包封率envelopment ratio 包封率envelopment protection 环保site envelopment 释义包膜位置 返回 envelopment