What is the 'biggest city in the world? That is, (21) city has the largest population? This seems like (22) question to answer, but actually it isn't.It's actually rather difficult to say which cities (23) the largest. There are two reasons for this diffi
题目
What is the 'biggest city in the world? That is, (21) city has the largest population? This seems like (22) question to answer, but actually it isn't.
It's actually rather difficult to say which cities (23) the largest. There are two reasons for this difficulty. First of all, it isn't easy to determine a city's boundaries, that is, where a city ends. Nowadays, nearly all cities have a large (24) area around them. So when we talk about the population of a city, we often mean the population of the whole metropolitan area around the city. That means that it's difficult to determine what the population of a city is because it's difficult to define what a city is.
The second reason that it is difficult to 25 the population of different cities is this: it is almost impossible to get (26) about the population of all cities for the same year. For example, we might get an estimate of New York's population in 1979 and an (27) of Mexico City's population in 1981. So we real ly can't compare the numbers because the information is for (28) different years. And the population of cities changes rather quickly, especially in some cases. For example, the population of Jakarta, Indonesia, may increase by 5% each year, so the population figure will change rather quickly.
So we can say that these are our two (29) for comparing the populations of cities: one, it's difficult to determine the (30) of a city, and two, it is difficult to get accurate information.
21. A. what
B. which
C. where
D. how
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更多“What is the 'biggest city in the world? That is, (21) city has the largest population? Thi ”相关问题
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第1题：
关系模式CSZ(CITY，ST，ZIP)其属性组上的函数依赖集为F＝{(CITY，ST)→ZIP， P→CITY}，关系模式CSZ的主属性是
A．ZIP
B．CITY，ST，ZIP
C．CITY，ZIP
D．ST，ZIP
正确答案：B
解析：包含在任何一个候选码中的属性叫做主属性。在这道题中全部属性都是主属性。 -
第2题：
某销售公司数据库中的关系零件为P(Pno, Pname, Sname, City, Qty)，Pno表示零件号，Pname表示零件名称，Sname表示供应商，City表示所在地，Qty表示库存量。其函数依赖集F={Pno→Pname， (Pno,Sname)→Qty，Sname→City}。关系P为 （ ），存在冗余度大、修改操作不一致、插入异常和删除异常的问题。若将P分解为（ ），则可以解决这一问题。
A.1NF B.2NF C.3NF D.4NF A.P1(Pname, Qty)、P2(Pno,Sname,City) B.P1(Pname, Pname)、P2(Sname,City,Qty) C.P1(Pno, Pname)、P2(Pno,Sname,Qty) 、P3(Sname,City) D.P1(Pno, Pname)、P2(Pno, Qty)、P3(Sname,City)、P4(City,Qty)
正确答案：A,C
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第3题：
3、英雄城市 译文：____________ city
错误 -
第4题：
关系模式CSZ(CITY,ST,ZIP）其属性组上的函数依赖集为F={(CITY,ST）→ZIP,ZIP→CITY},关系模式CSZ的主属性是
A．ZIP
B．CITY,ST,ZIP
C．CITY,ZIP
D．ST,ZIP
正确答案：B
解析：本题主要考查了对函数依赖和主属性的理解。 包含在任何一个候选码中的属性叫做主属性。在这道题中全部属性都是主属性。 -
第5题：
销售公司数据库中的关系零件为P(Pno,Pname,Sname,City,Qty)，Pno表示零件号，Pname表示零件名称，Sname表示供应商，City表示所在地，Qty表示库存量。其函数依赖集F={Pno→Pname，(Pno,Sname)→Qty，Sname→City}。关系P存在冗余度大、修改操作不一致、插入异常和删除异常的问题。若将P分解为（45），则可以解决这一问题。A.P1(Pname,Qty)、P2(Pno,Sname,City)
B.P1(Pname,Pname)、P2(Sname,City,Qty)
C.P1(Pno,Pname)、P2(Pno,Sname,Qty)、P3(Sname,City)
D.P1(Pno,Pname)、P2(Pno,Qty)、P3(Sname,City)、P4(City,Qty)答案：C解析：原零件关系P存在非主属性对码的部分函数依赖：（Pno, Sname) —>Qty,但是Pno ——>Pname、Sname —>City,因此P∈1NF，而非2NF的。1NF主要存在冗余变大、修改操作的不一致、插入异常和删除异常的问题。
分解后的关系模式P1P2和P3消除了非主属性对码的部分函数依赖，同时不存在传递依赖，故达到3NF。 -
第6题：
英雄城市 译文：____________ city
B