求详细解释分析一句英语

这句话 是典型的 句子套句子。the reason often given for the low regard in which smell is held is that 。。可以分为以下几层,第一层是 the reason is that,所以要用 is ,第二层是regard in which smell is held , in which smell is held 是定语从句,先行词是 regard。第三层,often given for the low regard 是the reason 的后置定语。希望能帮到你哈~