历年计算机等级考试四级一8

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(64)What is the contrapositive of the following implication？
“If it is raining，then I get wet.”
A)If I get wet，then it is raining.
B)If I am wet ，then if is raining.
C)If it is not raining,I do not get wet.
D)If I do not get wet，then it is not raining.
(65)Which property does R posses？
Let A=｛1，2，3，4｝and let R =｛〈1，2〉，〈2，2〉，〈3，4〉，〈4，1〉｝
A)Symmetry B)Reflexivity C)Asymmetry D)Antisymmetry
(66)When walking a tree,which traversal method yields a prefix,or Polish,form？
A)lnorder B)Preorder C)Postorder D)Reorder
(67)ln the following statements about graph operations,which one isNOT correct？(2 grades)
A)Spanning tree of a graph may not be unique.
B)Minimum spanning tree of a graph may not be unique.
C)Finding critical path is an operation on directed graph.
D)Finding critical path is an operation on undirected graph.
(68)Which traversal method for a binary tree does the following Pascal
code illustrate？(2 grades)
procedure traverse(p:pointer)；
begin 
if p《》nil
then begin
traverse(p↑。left)；
process(p)；
traverse(p↑。right)
end
end
A)lnorder B)Preorder C)Postorder D)Reorder
(69)What storage scheme does ＭＳ－ＤＯＳuse for storing
files on a disk？
A)l——nodes B)a linked list allocation
C)a continuous allocation D)a linked list with index
(70)Which of the followings is ＮＯＴa condition for deadlock？
A)Starvation B)Circular Wait
C)NO Preemption D)Mutual Exclusion
(71)Assume that an operating system uses a round——robin scheduler.The
process's quantum is 20 msec,and the context switch is 5 msec.What percentage of the 
context switch is 5 mesc.What percentage of the Ｃ
ＰＵ's time is spent on administrative overhead？(2 grades)
A)5％B)15％C)20％D)25％
(72)What state is a process in when it can't run because it needs a
resource to become available？(2 grades)
A)Ready B)lnterrupt C)Blocked D)Running
(73)The following sectors are requested from the disk:
11  ,1,36,16,34,9,12
What is the order of the sector reads if you are using the elevator
algorithm？(2 grades)
A)1,9,11,12,16,34,36 B)11,1,36,16,34,9,12
C)11,12,9,16,1,34,36 D)11,12,16,34,36,9,1
(74)What is the candidate key of a relational database？
A)A field with a constraint placed on it.
B)A set of fields that have no data in them.
C)A set of fields in a table used to identify a record uniquely.
D)Fields from multiple tables that are used for sorting records.
(75)What Normal From is the table shown in the exhibit？(2 grades)
┌──────────────────────┐
│┌──────────────────┐│
││emps tbl ││
│├──────────────────┤│
││emp_id ││
││emp_name ││
││emp_phone ││
││dept_name ││
││dept_phone ││
││dept_mgrname ││
│└──────────────────┘│
│(1)emp_id→emp_name,emp_phone,dept_name │
│(2)dept_name→dept_phone,dept_mgrname │
└──────────────────────┘
A)1NF B)2NF C)3NF D)BCNF
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