键码的定义：在实体集的范围内惟一标识 ______ 。

根据首字母填词

My n 小题1:  is Andy. I a 小题2:  thirteen. I have a sister. She h 小题3: long black hair.So there are four people in my f 小题4: . My f 小题5: lessons are Maths and English. At weekends,we s小题6: in the supermarket.That makes me f 小题7: happy. I often play football w 小题8:  my classmates. My parents are teachers. They teach English in a middle school. They like sports.They are in the school basketball t 小题9: . They are my h 小题10:.