（1）设计能够表示出班级与学生关系的数据库。 （2）设计能够表示学校与校长关系的数据库。 （3）设计医院病房计算机管理数据库。-(1) designed to show the relationship between class and student database. (2) designed to express the relationship between the school and the principal database. (3) design database

把从C语言库中随机给的15个数每5个一行输出，并把每3个数相加的和再进行输出.-Random from the C language library to 15 the number 5 line of output, and the sum of every three number and then output.