下列语句中，可删除sc表中idx_sc索引的语句有 （ ）</p>

Cu、Al、Ti、V、Mn、P和Sc等元素在中含量最高

下列哪个特征数中包含对流传质系数kc A: Sc B: P C: Le D: Sh

糖类不含有，脂质不一定有，蛋白质也不一定有，而核酸一定有的元素是(　　)A．N　　　B．SC．P　　　D．Fe

假定： A: S B: C，SC C: S，SC D: S，C，SC

检索选修课程‘C2’的学生中成绩最高的学生的学号。正确的select语句为（ ）。 A: select S B: from sc where C C: =‘C2’and grade>= (select grade from sc where C D: =‘C2’) E: select S F: from sc where C G: =‘C2’and grade in (select grade from sc where C H: =‘C2’) I: select S J: from sc where C K: =‘C2’and grade not in (select grade from sc where C L: =‘C2’) M: select S N: from sc where C O: =‘C2’and grade>=all (select grade from sc where C P: =‘C2’)

检索选修“C2”课程的学生中成绩最高的学生的学号。正确的SELECT语句是（ ）。 A: SELECT s B: FROM sc WHERE c C: =’C2’ AND grade＞＝(SELECT grade FROM sc WHERE c D: =’C2’); E: SELECT s F: FROM sc WHERE c G: =’C2’ AND grade IN(SELECT grade FROM sc WHERE c H: =’C2’); I: SELECT s J: FROM sc WHERE c K: =’C2’ AND grade NOT IN(SELECT grade FORM sc WHERE c L: =’C2’); M: SELECT s N: FROM sc WHERE c O: =’C2’ AND grade＞＝(SELECT max(grade) FROM sc WHERE c P: =’C2’);

LC和SC分别具有几个工作站系统（） A: LC:3,SC:3 B: LC:4,SC:2 C: LC:2,SC:4 D: LC:4,SC:3

<p>下列离子中，半径最小的是</p> A: Ti<sup >4+</sup> B: K⁺ C: Sc<sup >3+ </sup> D: Ca<sup >2+</sup>

检索选修课程号为“D3”的学生中成绩最高的学生的学号，正确的、SELECT语句是______ A: SELECT S# B: FROM SC C: WHERE C#='D3'AND GRADE＞= D: (SELECT GRADE FROM SC E: WHERE C#='D3')； F: SELECT S# G: FROM SC H: WHERE C#='D3'AND GRADE IN I: (SELECT GRADE FROM SC J: WHERE C#='D3')； K: SELECT S# L: FROM SC M: WHERE C#='D3'AND GRADE NOT IN N: (SELECT GRADE FROM SC O: WHERE C#='D3')； P: SELECT S# Q: FROM SC R: WHERE C#='D3'AND GRADE＞=ALL S: (SELECT GRADE FROM SC T: WHERE C#='D3')；