杭钢20万m3稀油式高炉煤气柜的底部油沟液位约为多少mm?()
A.430
B.470
C.510
D.550
参考答案:C
下列程序的输出结果是______。 main() { int i,j;for(j=10;j<11;i++){ for(i=9;i<j;i++) if(!(j%i))break; if(i>=j-1)printf(”%d”,i);} }
A.11
B.10
C.9
D.10 11
现在有两个关系模式:供应商S(Sno,Sname,Status,City)和供应情况SPJ(Sno,Pno,Jno, Qty)。对于查询“查询零件号Pno等于‘P3’的供应商名Sname”SQL语句 (221) 是错误的,而关系代数表达式 (222) 是正确的。
A.SELECTSname FROM S WHERE EXIST5 (SELECT * FROM SPJ WHERE S.Sno=SPJ.Sno AND SPJ.Pno=’P3’)B.SELECT Sname FROM S,SPJ WHERE S.Sno=SPJ.Sno AND SPJ.Pno=’P3’) CROUP BY SnameC.SELECT DISTINCT Sname FROM S WHERE EXISTS (SELECT * FROM SPJ WHERE S.Sno=SPJ.Sno AND SPJ.Pno=’P3’)D.SELECT DISTINCT Sname FROM S WHERERE 0< (SELECTCOUNT(,) FROM SPJ WHERE S.Sno=SPJ.Sno AND SPJ.Pnn=’P3’)