说明：  四位分别来自中国、美国、俄罗斯、加拿大的小学生都以自己的国土面积大而骄傲不已， 但是他们想知道到底谁的国土最大，谁的最小，他们的判断如下： 加拿大学生：加拿大最大，美国最小，俄罗斯第三。 美国学生：美国最大，加拿大最小，俄罗斯第二，中国第三。 中国学生：美国最小，加拿大第三。 他们互不相让，最后老师下定结论：对于上述四国面积的判断，他们每人只判断对了一个国家。
(Four were from China, the United States, Russia, Canada pupils have their own pride endless land area, but they want to know in the end who is the largest land, who' s the smallest, their judgment is as follows: Canada Student: Canada' s largest, the United States minimum, Russia third. American students: the largest U.S., Canada' s smallest, Russia second and China third. Chinese students: American smallest, Canada third. They refused to give teachers make up the final conclusion: For the area of ​ ​ the four countries of judgment, judgment on each of them only one country.)