In which of the following situations should correlation names be used?()A.A table referenced in the FROM clause has no indexed column.B.The table referenced in the FROM clause has more than 200 columns.C.Two or more tables in the FROM clause have identica

题目
In which of the following situations should correlation names be used?()

A.A table referenced in the FROM clause has no indexed column.

B.The table referenced in the FROM clause has more than 200 columns.

C.Two or more tables in the FROM clause have identical column names.

D.The FROM clause contains two or more tables in the SELECT statement.


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    As a police officer, you are trained to stay calm even in extremely (danger) ___________situations.


    正确答案:dangerous

  • 第2题:

    ________ the vessel have no safety radiotelegraphy certificate at the time of her delivery,she ________ be held to be unseaworthy.

    A.If/may

    B.Will/shall

    C.Should/would

    D.Would/should


    正确答案:C

  • 第3题:

    I__________have been there,but I__________not find the time.

    A.should;would
    B.should;could
    C.might;could
    D.could;could

    答案:B
    解析:
    考查情态动词的用法。句意为:“我本应该去那里,但我没时间。”should have done表示“过去本应做的事而实际上并没有做”,常含有责备、遗憾的语气。

  • 第4题:

    下面哪一个是错误的?

    A.使用len(列表名)测量元素的个数names_list=["zhangsan","lisi","wangwu"]print(len(names_list))

    B.使用列表名[下标]获取列表的某个元素,例如:names_list=["zhangsan","lisi","wangwu"]print(names_list[2])

    C.向列表中添加新元素有三个方法:append、extend、insert,例如:names_list=["zhangsan","lisi","wangwu"]names_list.append("zhaoliu")names_list.extend(["zhaoliu","liqi"])names_list.insert(1,"zhaoliu")print(names_list)

    D.已有列表nums=[11,22,33,44,55],使用while循环遍历列表nums=[11,22,33,44,55]i=0 whilei

    print(nums[i])i+=1


    正确答案:D

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    ______ it rain tomorrow moring, the loading ______.

    A.Should / will be postponed

    B.If / shall be postponed

    C.Should / would be postponed

    D.If / has to be postponed


    正确答案:C
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  • 第6题:

    多选题:下面哪个是错误的用python实现存储n个人的姓名?

    A.names1=n*[0] for i in range(n): names1[i]=input('输入{}个人的姓名:'.format(i+1))

    B.names2=[] for i in range(n): names.append(input('输入{}个人的姓名:'.format(i+1)))

    C.names3=[] for i in range(n): name=input('输入{}个人的姓名:'.format(i+1)) names3+=name

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    Python 中的变量赋值需要数据类型声明