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更多“设s="HE IS A WORKER",t="WORKER"。则index(s,t,5)的返回值是()。 A.4B.5C.6D.9E.10”相关问题
  • 第1题:

    设关系R与关系S具有相同的目,且相对应的属性的值取自同一个域,则R ∩ S可记作

    A.{t | t ∈R ∨ t ∈S}

    B.{t | t ∈R ∧ tS}

    C.{t | t ∈ R ∧ t ∈ S}

    D.{t | t ∈ R ∨ tS}


    正确答案:C
    解析:交运算是求两个关系中公共的元组。设有两个结构相同的关系R和S,R和S的交记为R∩S,其结果是一个新关系,有既属于R又属于S的元组组成,可记为R∩s{t │ t∈R∧t∈S}。

  • 第2题:

    Even though he's ______ out of college and still a bit green, he is a great co-worker.

    A flesh ;

    B fresh ;

    C flash


    参考答案:B

  • 第3题:

    设关系R和关系S的元素分别是4和5,关系T是R与S的笛卡尔积,即:T= R×S,则关系T的元数是( )。

    A.9

    B.16

    C.20

    D.25


    正确答案:C

  • 第4题:

    设关系R、s和T分别如下图所示,其中T是R和S的一种操作结果。则

    A.T=R ∞S

    B.T=R∞SC<E R.B=S.B

    C.T=R ∞s

    D.T=R×S


    正确答案:A
    解析:关系R和s连接,同时约束条件是“C<E’,即可得到关系T。因此,本题答案为A)。

  • 第5题:

    设关系R和S的元数分别是r和s,则集合{t|t=∧tr ∈R∧ts∈S}标记的是A.R∪SB.R-SC.R∩SD.R×S

    设关系R和S的元数分别是r和s,则集合{t|t=<tr,ts>∧tr ∈R∧ts∈S}标记的是

    A.R∪S

    B.R-S

    C.R∩S

    D.R×S


    正确答案:D
    解析:本题考查集合运算。集合的并:R∪S={t|t∈R∨t∈S},集合的差:R-S={t|t∈R∨t S},集合的交:R∩S={t|t∈R ∧t∈S},集合的广义笛卡尔积:R×S={t|t=tr, ts>∧tr∈Rts∈S}。正确答案为选项D。

  • 第6题:

    ( 35 )设关系 R, S 和 T 分别如下图所示,其中 T 是 R 和 S 的一种操作结果。则


    正确答案:A

  • 第7题:

    设关系R和关系S的元数分别是5和4,关系T是R和S的广义笛卡尔积,即:T=R×S,则关系T的元数是( )。

    A.7

    B.9

    C.12

    D.16


    正确答案:B
    解析:广义笛卡尔积是指关系R和关系S联接,也就是把关系R中的各元组和关系S中的各元组分别合并,所以关系T的元数为9。

  • 第8题:

    ● 设关系R是4元关系,关系S是一个5元关系,关系T是R与S的笛卡尔积,即T=R×S,则关系T是 () 元关系。()A.9 B.11 C.20 D.40


    正确答案:A
    根据笛卡尔积的定义:有n元关系R及m元关系S,它们分别有p\q个元组,则关系R与S经笛卡尔积记为RXS,该关系是一个n+m元关系,元组个数是pXq,由R与S的有序组组合而成。

  • 第9题:

    In this passage, the following advantages of casual office wear are mentioned EXCEPT___________.

    A.saving worker's money
    B.making workers more attractive
    C.improving worker's feeling
    D.making workers happier

    答案:B
    解析:
    文章中提到,穿便装可以节省钱,可以使员工工作的时候更舒服,也可以使他们开心,并没有提到可以让他们变得更有吸引力。故答案选B。

  • 第10题:

    单选题
    A test in industrial psychology is used to find out _____.
    A

    a worker's achievements

    B

    a worker's potential for a certain job

    C

    a worker's psychological problem

    D

    a worker's motivation for a certain job


    正确答案: B
    解析:

  • 第11题:

    单选题
    In an industrial psychologist's mind, all of the following is important EXCEPT _____.
    A

    the steps in which work is done

    B

    the state of mind of a worker when working

    C

    the effect of working environment on a worker

    D

    the value of the product a worker is making


    正确答案: C
    解析:

  • 第12题:

    单选题
    若INDEX(S,T)表示求T在S中的位置的操作,则对于S=“Beijing&Nanjing”,T=“jing”,INDEX(S,T)=()
    A

    2

    B

    3

    C

    4

    D

    5


    正确答案: C
    解析: 暂无解析

  • 第13题:

    Henry's job was to examine cars which crossed the frontier to make sure that they were not smuggling anything into the country. Every morning,except at weekends,he (11) see a factory worker coming up the hill towards the frontier, (12) a bicycle with a big load of old straw on it. When the bicycle arrived the frontier,Henry used to stop the man and order him to take the straw off. Then he would examine the straw very carefully to see (13) he could find anything,after which he would look in all the man's pockets before he let him tie the straw up again. The man would then put it on his bicycle and go off down the hill with it. Although Henry was always (14) to find gold or jewelry or other valuable things hidden in the straw,he never found (15) ,even though he examined it very carefully. He was sure that the man was smuggling something,but he was not (16) 鱼to imagine what it could be.

    Then one evening,after he had looked through the straw and emptied the factory worker's pockets (17) usual,he said to him,“Listen,I know that you are smuggling things (18) this frontier. Won't you tell me what it is that you're bringing into the country so successfully? I'm an old man,and today's my last day on the job. Tomorrow I'm going to (19) . I promise that I shall not tell anyone if you tell me what you've been smuggling. ”The factory worker did not say anything for (20) . Then he smiled,turned to Henry and said quietly:“Bicycles. ”

    A. should

    B. might

    C. would

    D. must


    正确答案:C
    [解析] 情态动词would用以表达习惯性“总是,总会”。

  • 第14题:

    He doesn’t believe the worker can ____________ to assemble the motorcycle all by himself.

    A、succeed

    B、pursue

    C、manage

    D、handle


    参考答案:C

  • 第15题:

    设s="HE IS A WORKER",t="WORKER"。则StrIndex(s,t,5)的返回值是()。

    A.4

    B.5

    C.6

    D.9

    E.10


    参考答案:D

  • 第16题:

    设关系R与关系S具有相同的目,且相对应的属性的值取自同一个域,则R∪S可记作

    A.{t | t∈R∨t∈S}

    B.

    C.{t | t∈R∧t∈S}

    D.


    正确答案:A
    解析:A)为并,B为差,C为交,D都不属于。[考点链接]传统的集合运算、专门的关系运算。

  • 第17题:

    设关系R是4元关系,关系S是一个5元关系,关系T是R与S的笛卡儿积,即T=R×S,则关系T是______元关系

    A.9

    B.11

    C.20

    D.40


    正确答案:A
    解析:根据笛卡儿积的定义:有n元关系R及m元关系S,它们分别有p、q个元组,则关系R与S经笛卡儿积记为R×S,该关系是一个n+m元关系,元组个数是p×q,由R与S的有序组组合而成。答案选A。

  • 第18题:

    设关系R与关系S具有相同的目,且相对应的属性的值取自同一个域,则R∩S可记作________。

    A.{t|t∈R∨t∈S}

    B.{t|t∈R∧t┐∈S}("┐∈"表示"不属于")

    C.{t|t∈R∧t∈S}

    D.{t|t∈R∨t┐∈S)("┐∈"表示"不属于")


    正确答案:C
    解析:设关系R和关系S具有相同的目n(即两个关系都有n个属性),且相应的属性取自同一个域,则关系R与关系S的交集由既属于R又属于S的元组组成。其结果仍为n目关系。记作:R∩S={t|t∈R∧t∈S}。

  • 第19题:

    函数strcmp( )的功能是对两个字符串进行比较,当s所指字符串和t所指字符串相等时,返回值为0;

    当s所指字符串大于t所指字符串时,返回值大于0;当s所指字符串小于t所指字符串时,返回值小于

    0(功能等同于库函数strcmp( ) ),请填空。

    include <stdio.h>

    int strcmp ( chat * s, char * t)

    { while( * s && * t && * s=【 】

    { s++;t++; }

    return 【 】;

    }


    正确答案:* 或t[0] * s- *t 或 * s-t[0]或s[0]- * t或s[0]-t[0]
    * 或t[0] * s- *t 或 * s-t[0]或s[0]- * t或s[0]-t[0] 解析:对字符串比较的方法是依次对两字符串对应位置上的字符两两比较,当出现第一对不相同的字符时,即由这两个字符(ASCⅡ码值)决定所在串的大小。

  • 第20题:

    A

    In a small village, there is a teacher, a nurse(护士) ,a driver(司机) and a worker.They are good friends. What are their names? One is Mike, one is Jack, one is Tom and the other is John. Mike's, Jack’s and Tom-s children are classmates. John doesn’t have any children He teaches his friends' children at school. Mike has many hens. He gives the driver and the nurse eggs. Jack's child goes to the nurse- s house. The nurse-s house is beside Jack's.

    ( )21. Are the four people good friends?

    A. Yes.

    B. No.

    C. Not.

    D. They are brothers.


    正确答案:A
    21.A【解析】根据文章的第二句可知。

  • 第21题:

    若INDEX(S,T)表示求T在S中的位置的操作,则对于S=“Beijing&Nanjing”,T=“jing”,INDEX(S,T)=()

    • A、2
    • B、3
    • C、4
    • D、5

    正确答案:C

  • 第22题:

    问答题
    What’s the difference between “postal worker” and “postman” according to the passage?

    正确答案: The former is formal, the latter is informal.
    解析:
    事实细节题。根据第四段“You would be quite likely to read in the paper that ‘Postal workers are to receive a pay increase’ But ‘Has the postman been?’ would be most likely to be heard in informal conversation.”可以得出结论,postal worker是正式的书面用法,而postman则是非正式的口语用法。

  • 第23题:

    单选题
    设关系R和S的元数分别是r和s,则集合{t|t=t,ts>∧tr∈R∧ts∈S}标记的是()。
    A

    R∪S

    B

    R-S

    C

    R∩S

    D

    R×S


    正确答案: D
    解析: 暂无解析