答案：D

题目分析：句意：如果昨天你动身走了，那么你现在就能和你的妈妈说话了。这是错综虚拟语气，从句是对过去的虚拟，所以用过去完成时，主句是对现在的虚拟，所以用would+动词原形。

点评：本题较难。错综虚拟对于学生来说是难点，虚拟语气是高中阶段的重要语法项目，需要考生牢记各种情况的虚拟语气的谓语动词的形式，并要有分析理解语境的能力。

即学即练：If you _______to the teacher carefully yesterday, you _______ how to do the exercise now.

A．listened; would know

B．had listened; would be knowing

C．listened; would have known

D．had listened; would know

解析：D。句意：如果你昨天认真听了老师的讲话，你现在就知道如何做这道题了。