Throughout history, it has been those who have questioned conventional wisdom and those who have challenged our common-sense notions of the world that have been the ones to have ushered in the major advancements of human civilization.
请问老师这是一个强调句结构现象吗【It has been those who / that have done sth】?学生没有找到关于现在完成时态的强调句语法知识的介绍,对这个句子的时态现象感到疑惑。