学员疑问：There would seem to be no reason why organ removal for transplantation purposes should not also be acceptable to public opinion, provided there is a mechanism by which individuals in their lifetime can refuse this permission. 老师，这句话中provided是什么用法？是非谓语动词吗？

老师解答：这个句子中provided不是非谓语动词的过去分词形式，而是一个连词（conj.）相当于if，引导条件状语从句， provided后面也可以接个that，即provided或provided that引导条件状语从句。以上句子意思是：倘若个人在他们有生之年可以拒绝这种许可，那么公众没有理由不该接受器官移植。

点评分析：这里还需要注意的是，这种provided 或provided that也可以是providing或providing that，这两种是一样的用法。