If the south had won the war, what is now the United States _____ divided into several countries.A. will beB. might have beenC. should beD. must have been 答案:D 虚拟语气,与过去事实相反用过去完成时态。 下列关于生物圈的说法,错误的是( ) A.生物圈是地球上所有生物的共同家园 B.生物圈是地球上所有生物与其生存环境的整体 C.生物圈是最大的生态系统 D.生物圈中的大气圈、水圈和岩石圈是截然分开的