We have hesitated for about a month. But it's high time that w

We have hesitated for about a month. But it's high time that we _______ about whether or not to buy the house.
A、make up our mind
B、will make up our mind
C、made up our mind
D、have made up our mind
【正确答案】：C
【名师解析】:题目中的"It's high time that"结构要求从句使用虚拟语气，即谓语动词用过去式。因此，正确的选项是C.made up our mind，表示“我们早该下定决心了”。其他选项要么时态不正确，要么结构不符合虚拟语气的用法。