【选项释义】 A. Had they arrived过去完成时 B. Were they arriving过去进行时 C. Would they arrive一般过去时 D. Were they to arrive过去将来时 【考查点】虚拟语气 【解题思路】主句表达主观愿望或某种强烈的感情且主句谓语是“should+动词原形”,故这里要用虚拟语气。从句部分是倒装结构,省略了if,由于句子中的时间状语是the day after tomorrow,所以从句动词应该用与将来事实可能相反的虚拟语气,应为should(were to)+动词原形,故D项正确。 【干扰项排除】A、B、C选项不符合语法逻辑。 【句意】如果他们能在我们后天出发之前到达,我们就能举行一场精彩的晚宴了。