[单选题]If he had been working hard, he ______ in the office now. However, he didn’t.
A.would be working
B.were to be working
C.was working
D.should work

参考答案:A

【详解】
考查虚拟语气。句意：如果他过去一直努力工作，现在就坐在办公室工作了。然而，他没有。根据“However, he didn’t.”可知，此句是混合虚拟语气。If从句与过去事实相反，主句与现在事实相反。与现在相反的虚拟语气的主句可用would/could/ might +动词原形。根据语境及时间状语“now”可知，此处是指现在正在工作，因此要用进行时，故选A。
【点睛】
一、虚拟语气在if引导的条件句中的用法
虚拟语气用于表示说话人所说的并不是事实，而是一种假设或愿望，往往与事实相反。
1表示与现在事实相反的虚拟条件句
If+主语+动词的过去式（be用were），主语+would(should/ could/might)+动词原形
1) If I were you, I would study English.如果我是你，我就会学英语。
2)I would certainly go if I had time.如果有时间的话，我一定会去的。
2表示与过去事实相反的拟条件句
If+主语+ had done，主语+would（should /could/ might）+ have done
1) If you had taken my advice, you would not have missed the test. 如果你接受了我的建议，你就不会错过考试。
3表示与将来事实相反的虚拟条件句。
If+主语+should（were to）+动词原形/动词的过去式，主语+would（could /should /might）+动词原形。
If it were to rain tomorrow, the meeting would be put off. 如果明天下雨，会议就会推迟了。
二、 错综时间虚拟条件句。即条件从句与主句所指时间不一致，如从句指过去，而主句即指的是现在或将来，此时应根据具体的语境情况，结合上面提到的三种基本类型对时态作相应的调整：
If it had rained last night, the ground would be wet now. 要是昨晚下雨的话，现在地面就会是湿的。