. he had not hurt his leg John would have won the race. A. IfB. SinceC. ThoughD. When

问题补充：

. he had not hurt his leg, John would have won the race.

A. If

B. Since

C. Though

D. When

答案：

(答案→)A. If

B. Since

C. Though

D. When

解析：if在此引出一个虚拟条件。又如：If he had asked me, I would have had to tell him the truth. 如果他问我，我就不得不告诉他真相了。If I had not got married, I would still have been living abroad, 如果我没结婚，我就会仍然住在国外。