题目内容：

the question arose who was the first to reach the top急!
这句网上有人说who was the first to reach the top是question的同位语,我查了下,好像who不引导同位语从句,如果可引,那么怎么和引导词that区分?如果不可引,同位语的引导词又不省略,怎么解释?急用,谢谢