DR设备的安装缩光器照射野和指示灯照射野应一致，允许误差值为（） A: <1%SID B: <2%SID C: <3%SID D: <5%SID

【填空题】阅读程序写结果 public class Student { private static int sid = 0; private String name; int id; Student(String name) { this.name = name; id = sid++; } public void info() { System.out.println("My name is "+name+" No."+id); } public static void infoSta() { System.out.println(sid); } public static void main(String arg[]) { Student.sid = 100; Student st1 = new Student("huahua"); st1.sid = 2000; Student st2 = new Student("meimei"); st1.info(); st2.info(); } }

列表st定义为: <br/>st A: st$name B: st[[1]] C: st["name"] D: st[["name"]]

智慧职教: st=[["a","b"],"c"]st[0][1]='d'print(len(st),st)结果是

设置score表的sid列为外键，关联stu表的sid列，可以使用以下哪条命令实现。 A: alter table stu add constraint fk_sid foreign key(sid) references stu(sid); B: alter table stu add constraint fk_sid foreign key(sid) references score(sid); C: alter table score add constraint fk_sid foreign key(sid) references sore(sid); D: alter table score add constraint fk_sid foreign key(sid) references stu(sid);

设置score表的sid列为外键,关联stu表的sid列,可以使用以下哪条命令实现。() A: alter table stu<br> add constraint fk_sid foreign key(sid) references stu(sid); B: alter table stu<br> add constraint fk_sid foreign key(sid) references score(sid); C: alter table score<br> add constraint fk_sid foreign key(sid) references sore(sid); D: alter table score<br> add constraint fk_sid foreign key(sid) references stu(sid);

查询选修了2门课程以上的学生学号（） A: select sid,count(*) from sc group by sid having count(*)>=2 B: select sid,count(*) from sc group by sid where count(*)>=2 C: select sid,count(*) from sc where count(*)>=2 group by sid D: select sid,count(*) from sc group by cid having count(*)>=2

按照学号进行分组，统计学生的平均成绩（） A: select sid, avg(grade) from student group by cid B: select sid, avg(grade) from student group by sid C: select sid, avg(grade) from sc group by sid D: select sid, avg(grade) from sc group by cid

已知：struct st int n；struct st next；；static struct st a&#91;3&#93;=1,

经过以下栈的操作后，isEmpty(st)的返回值为（）。initStack(st);push(st,a);push(st,b);pop(st,x);pop(st,y); A: a B: b C: 1 D: 0