答案：A

题目分析：考查状语从句的省略句：while引导的时间从句在与主句（he made friends with the natives there）主语一致的时候，其主语和be动词可以省略，原句是While he is working in Scotland, he made friends with the natives there.省略后，就是while working…，句意：在英国的时候，他和当地人交朋友。选A。