Can you tell me ______ that the 29th Olympic Games will take place?

A．it is when

B．when is it

C．when is

D．when it is

危险与可操作研究（HOZAP）是一种以引导词为引导，对过程中工艺状态的变化加以确定，找到装置及过程中存在的危害的一种评价方法。