The guild principles of the tax plan released by the TD could have even greater significance for the economy than do the particulars of the plan. 白勇说: 若have 是实意动词, 则应当用do来代替 若have 是助动词, 则应当保留could 可是白勇书前面总结的时候是说,”主语谓语动词短语使用’助动词’或’情态动词’+v形式时,比较从句往往省略v, 保留助动词或情态动词”