●The constructcobeginStatement1;Statement2;coendmeans Statement1 and Statement2

●The construct

cobegin

Statement1；

Statement2；

coend

means 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

x=0；y=0；

cobegin

{x=1；y+=x；}

{y=2；x+=3；}

coend

Which of the following indicate(s)possible values for the variables when the segment finishes execution? (74) ．

Ⅰ．x=1，y=2

Ⅱ．x=1，y=3

Ⅲ．x=4，y=6

(74) A．Ⅰ

B．Ⅰ，Ⅱ

C．Ⅰ，Ⅲ

D．Ⅱ and Ⅲ

D【解析】译文：结构CobeginStatement1；Statement2；Coend的含义是语句1和语句2并行执行。结构中的两个原子操作是加载一个变量的值和存储一个变量的值。【程序段】ｘ＝０；ｙ＝０；ｃｏｂｅｇｉｎ｛ｘ＝１；ｙ＋＝ｘ；｝｛ｙ＝２；ｘ＋＝３；｝ｃｏｅｎｄ执行后，变量的值可能是哪个？先执行第二句再执行第一句，结果是II，否则结果是III。