全國計算機等級考試四級試題(四)

�牐�(61) The construct
�牐燾obegin
�牐燬tatement1;
�牐燬tatement2;
�牐燾oend
�牐爉eans Statement1 and Statement2 are to be executed in parallel. The only two atomic actions in this construct are loading the value of a variable and storing into a variable. For the program segment
�牐爔:=0；
�牐爕:=O；
�牐燾obegin
�牐燽egin
�牐爔:=l;
�牐爕:=y+x;
�牐爀nd;
�牐燽egin
�牐爕:=2;
�牐爔:=x+3;
�牐爀nd
�牐燾oend
�牐燱hich of the following indicate(s) possible values for the variables when the segment finishes execution?
�牐牏瘢畑=1,y=2
�牐牏颍畑=1,y=3
�牐牏螅畑=4,y=6
　　A．Ⅰ
　　B．Ⅰ and Ⅱ C)Ⅰ and Ⅲ
　　D．Ⅱ and Ⅲ

　　(62) Software maintenance is to do necessary modification,supplenemt, and completeness during software life circle. Among the following vary kinds of maintenance,which one has the maximum workload in a general way?
　　A．relevance maintenance
　　B．completeness maintenance
　　C．correctness naintenance
　　D．other kinds of maintenance

�牐�(63) Different quality factors of software can be reflected upon user’s different points of view,through product running,product modification and product transformation. Of the following properties,which one is connected with product running?
�牐牏瘢甤orrectness Ⅱ．robustness Ⅲ．re-use
　　A．Ⅰonly
　　B．Ⅱonly
　　C．Ⅰ+Ⅱ
　　D．a(chǎn)ll of above

�牐�(64) Let R and S be the relation respectively:
�牐燫elation R: A B C Relation S: B C D
�牐� 1 2 3 2 3 4
�牐� 6 7 8 2 3 5
�牐� 9 7 8 7 8 1
�牐燭he number of tuples that the result of the expression R ∞ S (Here is the natural join of relations R and S) is
　　A．3
　　B．4
　　C．6
　　D．9

�牐�(65) Suppose we have the relation schema R(A,B,C,
　　D．with functional dependencies;F{A→B,B→C,C→D,D→A},then R(A,B,C,D)at least is in
　　A．1NF
　　B．2NF
　　C．3NF
　　D．BCNF

�牐�(66) By means of multiple pipeline to carry out multiple processing,this technologyiscalled
　　A．Multiple pipeling
　　B．Superpipeline
　　C．Superscalar
　　D．Very long instruction word

�牐�(67) There are many page replacement algorithms in the page management. Most frequently used algorithm is
　　A．FIFO
　　B．PPT
　　C．OPT
　　D．LRU

�牐�(68) Layer n on one machine carries on a conversation with layer n on another machine. The rules and conventions used in this conversation are collectively known as the layer n
　　A．topology
　　B．protocol
　　C．service
　　D．peer

�牐�(69) Transport gateways connect byte streams in the transport layer. Application gateways allow interworking above
　　A．network layer
　　B．data link layer
　　C．transport layer
　　D．a(chǎn)pplication layer

�牐�(70) Every host and router on the Internet has an IP address, which encodes its
　　A．host number
　　B．host number and socket
　　C．network number
　　D．host number and network number