①KN0₃ ②NH₄Cl  ③CO（NH₂）₂ ④KCl ⑤NH₄H₂P0₄ ⑥Ca₃（PO₄）₂是常见的化学肥料，其中属于复合肥的是（　　）

A．①③

B．①⑤

C．②④

D．⑤⑥

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 thevalue of a variable and storing into a variable.For the program segment x:=0； y:=O； cobegin begin x:=l; y:=y+x; end; begin y:=2; x:=x+3; end coend Which of the following indicate(s) possible values for the variables when the segment finishes execution Ⅰ．x=1,y=2　　Ⅱ．x=1,y=3　　Ⅲ．x=4,y=6

A． Ⅰ

B． Ⅰ and Ⅱ

C． Ⅰ and Ⅲ

D． Ⅱand Ⅲ