英语半虚拟和跳层虚拟!!答:Mary couldn't have received my letter, otherwise she would have replied before now. (与过去事实相反) 六、名词从句虚拟语气 (1) ask, advise, beg, command, demand, decide, desire, insist, order, prefer, propose, require, recommend, request, suggest, urge等表示命令、要求、建议等含义的动词后...