what surprised us very much that he had passed the driving t

what引导主语从句：What surprised us very much is that he had passed the driving test。
it作形式主语：It surprised us very much that he had passed the driving test。
which引导非限制性定语从句：He had passed the driving test,which surprised us very much。
都可以译作：他通过了驾驶员行驶执照的考试,这使我们很诧异。