笔试选择题（81-90）

一、选择题:((1)-(90))题,分为1分题和2分题,满分120分.除标注2分题外,其它均为1分题.)

(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 earlierphases 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) th  e 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