记住一点就能判断：强调句it is XX……中强调的XX,是从句中的一个部分,从句本身不是一句完整句.（与原句相比）而非强调句that引导的从句是完整句,就像你给出的两句,都不是强调句.
还拿你的句子的一部分做例子,如：The building will be built in our school next year.
变为强调句：It is the building that will be built in our school next year.
It is in our school that the building wiil be built next year.
It is next year that the building wiil be built in our school.
另一句：It is he that failed in the final examination.
你注意一下,that 后面的句子与原句比完整吗,显然少了些什么吧.不是主语,就是状语、宾语.
另外还要注意的是,不管强调的是人、时间、地点还是事情,引导词都是that,而不能用who,when,who.