英语怪题,高手进!~It was in the hotel() he stayed和It was the hotel h

英语怪题,高手进!~
It was in the hotel() he stayed和It was the hotel he stayed
第一句话经鉴定where是可以的I can't find Mr. Smith.Where did you last see him this morning?--It was in the hotel() he stayed.
答案是where,为什么加了in和不加in都可以用where呢>?
第二句话也可以用where,那第二句话用that对不对,that引导的主语从句?