it is only when you have met with a failure___how to correct

題目：

it is only when you have met with a failure___how to correct your attitude
that you understand will you understand
why?

解答：

正確答案應該是前者.首先這是一個強調句型,it is...that...;第二,只有當only when放在句首時才需要倒裝,而這題並不是位於句首.