Bob insisted that his methord(was)pratical and his theory(be

Bob insisted that his methord(was)pratical and his theory(be published)in the book.
括号里填写的是正确答案,我不知道为什么,求高人用语法知识给我讲解这道题

insist 后接that从句,句中的时态可分为两种,像你的第一个空,作系表结构,“坚持觉得...”后面的句子不用虚拟,使用正常的时态,但第二空,“坚持认为...（应该）”则为虚拟语气,从句中用should +动词原形（should 可省略）
英语中类似的词还有suggest ,作暗示,表明讲时不虚拟,作“建议”讲时要虚拟.同上.
例如：the look on his face suggested that he passed the exam.
the teacher suggested that we (should) work hard to achieve our dreams.