第1题：
A.I realized
B.do I realize
C.I did realize
D.did I realize
第2题：
Only when I began to do it ____ that I had made a mistake.
A I realized B I had realized C did I realize D would I realize
第3题：
A.I opened
B. did I open
C. I had opened
D. had I opened
参考答案：D
第4题：
A、had I got
B、I had got
C、had I arrived in
D、I had arrived at
第5题：
Hardly _______ the railway station when the train started.
A.did I reach
B.had I reached
C.I reached
D.I had reached
第6题：
A、to be paid
B、get paid
C、that I receive the pay.
D、being paid
第7题：
Not until______ the whole thing to him ______that he was wrong.
A. had I explained, he realized
B. had I explained, that he realized
C. I had explained, that he realized
D. I had explained, did he realize
第8题：
此题为判断题(对，错)。
第9题：
A、Had you not given me
B、I had not given
C、You had not given me
D、Had I not given
答案：B
第10题：
A.If I had time, I would study French
B.If I have time, I will study French
C.If I had had time, I would have studied French
D.If I should have time, I would study French
答案：B
解析：条件句可分为两类，一类为真实条件句，一类为非真实条件句。非真实条件句表示的是假设或实际可能性不大的甚至完全不可能发生的情况，故采用虚拟语气。
A选项中，if+主语+一般过去时表示与现在事实相反，为虚拟语气；B选项中，if引导的是一个一般现在时的条件状语从句，为真实条件句；C选项中，if+主语+had done表示与过去事实相反，为虚拟语气；D选项中，if+主语+should do表示与将来事实相反，为虚拟语气。题干意为：下列条件句中那个是真实条件，所以答案选B。