第17题: [单项选择]The theme of this story is that______. A. those using logic are not always logical B. mysteries can always be solved by using logic C. detectives can never be trusted D. guilt can always be proved scientifically 参考答案:A 答案解析:主旨题。从文章开始神秘命案使人束手无策到大侦探的介入,使案情出现转机的是他捡到了一根头发,按逻辑,以此为线索就应该找到凶手,因此,他把注意的焦点放在人们的头发上。当他看见一个游客把头包在帽子里,又把帽