Teacher: Here are two birds, one is a swallow, the other is sparrow. Now who can tell us which is which?
Student: I cannot point out but I know the answer.
Teacher: Please tell us.
Student: The swallow is beside the sparrow and the sparrow is beside the swallow.老师： 这儿有两只鸟，一只是麻雀。谁能指出哪只是燕子，哪只是麻雀吗？
学生：我指不出，但我知道答案。
老师：请说说看。
学生：燕子旁边的就是麻雀，麻雀旁边的就是燕子。