皮皮学，免费搜题
登录
搜题
【单选题】
在student和sc表中查找选修002课程号的学生姓名，查询语句如下Select sname from student,sc where student.sno=sc.sno and cno=”002”如果student表有1000条学生记录，SC表有5000条选课记录，符合要求的选课记录有50条，一个块能装10条学生记录或100条选课记录，内存中留出10块用于存放选课记录、留出一块用于存放学生记录。如果按照自然连接-选择-投影的过程执行，如果一个块可以装10条连接结果记录，则在选择阶段需要读取的块数是多少？A.
550
B.
500
C.
1100
D.
2100
手机使用
分享
复制链接
新浪微博
分享QQ
微信扫一扫
反馈参考答案：
举一反三
【单选题】化妆品中含大量Bi、Al、Ca时，用原子吸收光谱法测定会干扰测铅的结果，这是因为
A.
它们影响铅的原子化
B.
它们的共振线接近铅的共振线
C.
它们原子化时，吸收大量能量，从而影响铅的测定
D.
它们的氧化物吸收铅的共振线
E.
它们改变了试样溶液的物理性质
【单选题】在何种情况下可利用图层和图层之间的裁切组关系创建特殊效果
A.
需要将多个图层同时进行移动基编辑
B.
需要移动链接的图层
C.
使一个图层成为另一个图层的蒙板
D.
需要隐藏某图层中的透明区域
【简答题】把打破化学键所需要的能量称为 。
【单选题】下列对摩尔(mol)的叙述不正确的是 [ ]
A.
摩尔是物质的量的单位，用于表示物质所含微观粒子的多少
B.
摩尔既能用来计量纯净物，又能用来计量混合物
C.
1mol任何气体所含的气体分子数目都相等
D.
用“摩尔”（而不用“个”）计量微观粒子与用“纳米”（而不 用“米”）计量原子直径，计量思路都是扩大单位
【简答题】董事会制度是确保股东充分行使权利最基础的制度安排。
【单选题】A car accident happened on the highway this morning. People took away the wounded to hospital immediately, and the government sent policemen there to cope with the event.
A.
A car accident was happened on the highway this morning. The wounded were immediately taken away to hospital, and the government were sent policemen there to cope with the event.
B.
A car accident was happened on the highway this morning. The wounded was immediately taken away to hospital by people, and policemen were sent there to cope with the event by the government.
C.
A car accident happened on the highway this morning. The wounded were immediately took away to hospital, and policemen were send there to cope with the event.
D.
A car accident happened on the highway this morning. The wounded were immediately taken away to hospital, and policemen were sent there to cope with the event.
【单选题】以下有关乳癌叙述不正确的是
A.
乳癌最常见的远处转移为肺、骨、肝
B.
乳癌早期表现为无症状性乳房肿块
C.
乳癌的大小决定其预后
D.
内分泌治疗是乳癌治疗的一个重要组成部分
E.
乳癌发病率与雌激素水平有明显关系
相关题目：
参考解析：
知识点：
题目纠错 0
发布
