已知Student类有一个属性__id，stu是Student类的对象，则通过“stu.__id='1810101'”可以将stu对象中的__id属性赋值为字符串'1810101'

A.a1

B.a2

C.b1

D.b2

A.Sno→Sdept

B.Sno→Mname

C.Sname→Sdept

D.（Sname，Cname）→Grade

A.#define STUDENT struct student STUDENT {int num; float age; }std1;

B.struct student {int num; float age; }std1;

C.struct {int num; float age; }std1;

D.struct int num; float age; }student; struct student std1;

A.a是指向X类对象的指针，用来作为Set()的形参

B.将X*a的计算结果传递给Set()函数

C.a是X类对象的引用，用来做为Set()的形参

D.以上都不对

A.alter table student change address stuAddress;

B.alter table student change address stuAddress varchar(50);

C.alter table student midify address stuAddress;

D.alter table student modify address stuAddress varchar(50);

A.候选键

B.主键

C.外键

D.连接码