全國計算機等級考試四級試題(三)

　　(62) How many subsets does A have?
�牐燣et A={E，O，A，W，P，V，B}
　　A．12
　　B．36
　　C．64
　　D．128

　　(63) Suppose V1=，V2=，where R is the set of real numbers，+， and· are respectively addition and multiplication.Let f﹕R→R and f(x) = ex， which of the following propositions is true?
　　A．f is a surjective homomorphism from V1 to V2
　　B．f is an injective homomorphism from V1 to V2
　　C．f is an isomorphism from V1 to V2
　　D．None of the above

　　(64) P(n) is the predicate ’if 4 divides n then 2 divides n’. What is the truth value of P(12)?
　　A．10
　　B．F
　　C．T
　　D．None of the above

　　(65) An algorithm to solve a given problem has time complexity
�牐燭(n)=nlog2n-(n-1)
�牐燝iven that the algorithm takes 0.8 second for a problem in which n =1024，how long should it take for a problem in which n=4096? (2 Points)
　　A．39 seconds
　　B．3.9 seconds
　　C．3.9 minutes
　　D．0.8 seconds

　　(66) What is the definition of a Path?
　　A．A sequence of vertices and the edges formed by each successive pair of vertices.
　　B．A walk with distinct vertices.
　　C．A walk with distinct edges.
　　D．None of the above

　　(67) The figure below shows a record used for recording information about a named event. Which of the following statement is incorrect? (2 Points)
�牐燰AR r﹕ record
�牐爀vent﹕array[1..10] of char;
�牐爌lace﹕array[1..20] of record
�牐爌lname﹕array[1..15] of char;
�牐燿ate﹕ array[1..5] of record
�牐爉o﹕1..12;
�牐燿ay﹕1..31;
�牐爕ear﹕integer
�牐爀nd
�牐爀nd
�牐爀nd;
　　A．This is a one-dimensional array of records，also called a table.
　　B．This is so called record of arrays;
　　C．The event can occur in up to 20 places and on up to 5 different dates in each place.
　　D．A reference to r.place[i].date[j].mo will access the month of the jth occurrence，in the ith place，of the event named in r.event.

　　(68) Which of the following statements is true regarding simple sort techniques? (2 Points)
　　A．Exchange sort is frequently referred to as a bubble sort.
　　B．Exchange sort is the least expensive.
　　C．If random data are in an array that is to be sorted，an Insertion Sort will give the best performance for large elements with small sort items.
　　D．Both Insertion Sort and Selection Sort require O(n)moves.

　　(69) Which UNIX command creates a symbolic link named myfile in the current directory to the file/etc/hosts?
　　A．In -s /etc/hosts myfile
　　B．In -s myfile /etc/hosts
　　C．link -s /etc/hosts myfile
　　D．link -s myfile /etc/hosts

　　(70) Which MS-DOS command is correct?
　　A．DEL /s *.bat
　　B．DEL *.exe/sp
　　C．DEL *.obj >nul:
　　D．DEL *.com *.sys

　　(71) A virtual memory system has five virtual pages numbered zero through four and three page frames. All the page frames are initially empty. How many page faults are generated with the following access sequence using a FIFO replacement policy? (2 Points)
�牐�0 1 2 3 0 1 4 0 1 2 3 4
　　A．8
　　B．9
　　C．10
　　D．11

　　(72) Which element is NOT part of a microkernel? (2 Points)
　　A．basic I/O
　　B．a(chǎn) file system
　　C．IPC mechanisms
　　D．memory management

　　(73) Which is local to a thread instead of a process? (2 Points)
　　A．a(chǎn) stack
　　B．a(chǎn)n open file
　　C．a(chǎn) semaphores
　　D．a(chǎn)n address space

　　(74) What is a subselect statement?
　　A．a(chǎn) select statement that selects a subset of fields in a table
　　B．a(chǎn) select statement that returns a subset of the data in a table
　　C．a(chǎn) select statement that appears within another select statement
　　D．a(chǎn) select statement that returns a subset of the constraints on a field

　　(75) In developing a hospital database，it is determined that on the average，each patient will have 6 treatments during a hospital stay. The averge length of a stay is three days.The hospital has 1000 beds. There are on the average 800 patients occupying beds each day. The relationship between PATIENT and TREATMENT is l: M. The relationship between PATIENT and BED is 1: 1， conditional. If treatment record occurrences are archived as soon as a patient is discharded from the hospital，how many occurrences of the TREATMENT records will be stored in the TREATMENT database file on the average? (2 Points)
　　A．6,000
　　B．4,800
　　C．18,000 D)1,600

　　(76) Which of the following conditions will make a relation that is in first normal form to be in second normal form?
�牐牏�.every non-key attribute is functionally dependent on the full set of primary key attributes.
�牐牏�.no non-key attributes exist in the relation.
�牐牏�.the primary key consists of only one attribute.
　　A．Ⅰ only
　　B．Ⅰand Ⅱ only
　　C．Ⅰand Ⅲ only
　　D．a(chǎn)ny of them

　　(77) The most commonly used locking level in implementing concurrency control is at which of the following levels?
　　A．database
　　B．table
　　C．record D)field

　　(78) Which function is NOT served by building a prototype?
　　A．It takes the place of the final system.
　　B．It assists in gathering software requirements
　　C．It assists in estimating the cost of the project.
　　D．It is used as the foundation of the larger projects.

　　(79) Software document is an important part of software and a basis of software development phase.It also influnces software’s (2 Points)
　　A．Reusability
　　B．Maintanence
　　C．Expansibility
　　D．Portability

　　(80) Which phase of the software development requires the most development time?
　　A．the design phase
　　B．the testing phase
　　C．the maintenance phase
　　D．the development phase

　　(81) Which of the following statements is correct? (2 Points)
　　A．The definition phase results in the Software Requirements Specification.
　　B．Testing is optional in software life cycle.
　　C．CASE tools can only aid in the design phase of a software life cycle.
　　D．A change during a later phase does not require the documentation of all earlier phases to be updated.

　　(82) Black-box and white-box testing method are often used in software testing phase，in which，the white-box is mainly used to test software’s
　　A．reasonableness of structure
　　B．correctness of a program
　　C．external function of a program
　　D．internal logic of a program

　　(83) How does Booth’s Algorithm improve binary multiplication?
　　A．It prevents overflow.
　　B．It prevents underflow.
　　C．It preserves the sign of the multiplication operation.
　　D．It enhances the speed of the operation significantly.

　　(84) A cache has 64 blocks; each block is 16 bytes. Which block does byte 1200 map to ?
　　A．25
　　B．60
　　C．75 D)100

　　(85) Which is NOT a characteristic of an RISC processor?
　　A．a(chǎn) high clock speed
　　B．a(chǎn) highly optimized pipeline
　　C．a(chǎn) few general-purpose registers
　　D．a(chǎn) limited amount of small instructions

　　(86) You are performing two sums: the first is a sum of two scalar variables and the second is a matrix sum of a pair of two- dimensional arrays-size 1000 by 1000. What speedup is achieved when the calculations are performed on size 1000 processors? (2 Points)
　　A．50
　　B．100
　　C．999
　　D．none of the above

　　(87) According to Shannon’s equation， what is the channel capacity of an analog voice-grade phone line with a bandwidth of 3100 Hz and a signal-to-noise ratio or 30dB? (2 Points)
　　A．9.1 Kbps
　　B．9.3 Kbps
　　C．30.9 Kbps
　　D．30.17 Kbps

　　(88) The X﹒25 standard specifies three layers of functionality. Which layers of the OSI model correspond to the X﹒25 layers?
　　A．the Physical，Network，and Session Layers
　　B．the Physical，Data Link，and Network Layers
　　C．the Physical，Data Link，and Transport Layers
　　D．the Physical，Session，and Presentation layers

　　(89) Which routing algorithm is described below?
�牐營t is a mechanism in which the setding station determines the route the frame will follow and includes the routing information with the frame; bridges read the routing information to determine if they should forward the frame.
　　A．Fixed Routing
　　B．Spanning Tree
　　C．Source Routing
　　D．Frame Forwarding

　　(90) Which OSI layer does a bridge operate at?
　　A．the Physical Layer
　　B．the Network Layer
　　C．the Transport Layer
　　D．the Data Link Layer