【正确答案】 D

【答案解析】该题是语法结构题，考查虚拟语气在含蓄条件中的用法。在此用法中，假设的情况不是用一个条件句来表示，而是隐含在诸如without，but for，but that等引导的短语或句子中，或由连词but，副词0therwise，以及比较等级等表示的上下文中，如：But that she was afraid, she would have gone there alone. 要不是因为害怕，她就独自一人去了。/A more careful person wouldn't have made so many mistakes. = If you had been mote careful, you wouldn't have made so many mistakes. 如果细心一点，就不会出这么多错误了。因此，根据题意和语法规则，选项D为最佳答案。