分析：with regard to sb/sth短语,意为：关于,至于 .however可视为插入语,whatever Futurist poetry maybe,even admitting that the theory on which it is based may be right由for引导是名词性短语,其中后半句话是that引导的作admit的宾语从句套on which引导的theory的定语从句.it can hardly be classed as literature,中it指代Futurist poetry ,be classed as 固定搭配,意思是：被划分为.
翻译：关于未来主义诗歌,然而,其根源（究竟为何物）是很难解释的,即便是基于众人认可的理论基础上,它（未来主义诗歌）也很难被划分为文学作品.