选择题：●The constructcobeginStatement1;Statement2;coendmeans Statement1 and Statement2 are to be

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