Whose 是物主词， 意为 of whom / which. 用在疑问句和关系从句中。 who's 是who is 或who has 的缩约式。试比较：
-- Whose it that coat ? 那件外套是谁的？
It was a decision whose importance was not required at that time. 这个决定，当时没有人认识到它的重要性。
DO you know anybody who's going to France in the next few days? 你知道有谁在今后几天到法国吗？