Which tire was flat——哪个车胎爆了？

　　Four students walked in halfway through the American history test my father was giving at the local community college. "Sorry," they said, "we had a flat tire.” An understanding man, Dad said that if they could all answer just one question correctly, he would give them each an A for the exam. The students agreed. So my father handed each one a piece of paper, placed them in four separate corners and said, "Write down which tire was flat."

　　我父亲在当地的社区大学教美国历史，（1次，）当测验进行到1半时，有四名学生才走进教室。“对不起，”他们说，“我们车子的1个轮胎爆了”。我父亲是1个通情达理的人，他说如果他们几个能正确地回答1个问题，他们的这次测验就能得到1个A。 那几个学生同意了。 我父亲递给他们每人1张纸，把他们安排在教室的四个角落，然后说，“写出是哪个轮胎爆了。”