They ______ so tired if they ______ for a whole day.

They ______ so tired if they ______ for a whole day.
A、wouldn't feel, didn't walk
B、wouldn't feel, weren't walk
C、wouldn't be feeling, weren't walking
D、wouldn't be feeling, hadn't been walking
【正确答案】：D
【题目解析】：该题考查错综复杂的虚拟语气。主句对现在进行假设，而从句是对过去进行假设，故选择D。本句的句意为“如果他们不是走了一整天的路，他们现在是不会那么疲惫的。”