Teacher: here are two birds, one is a swallow, and the other is a sparrow. Now who can tell us how to make a difference between them?
Sudent: 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，一只是燕子。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。