历年计算机等级考试四级三

(76)Which of the following conditions will make a relation that is in first normal form 
to be in second normal form?
Ⅰ.every non-key attribute is functionally dependent on the full set of primary key 
attributes.
Ⅱ.no non-key attributes exist in the relation.
Ⅲ.the primary key consists of only one attribute.
A) Ⅰ only B) Ⅰand Ⅱ only C) Ⅰand Ⅲ only D) any 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 high clock speed 
B) a highly optimized pipeline
C) a few general-purpose registers
D) a 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?
It 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