若 x 、 y 、 w 均是 int 型变量 , 以下正确的 switch 语句是
A.
switchx {case10:w=x+y;break; case11:w=y-x;break; default:w=x*y;}
B.
switch(x+y) {case11:w=y-x;break; case10:w=x+y;break; default:w=x*y;}
C.
switch(x*y) {case1:w=x+y; case2:w=y-x;break; case1+1:w=x*y;break;}
D.
switch(x) {casex:w=x+y;break; casey:w=y-x;break; default:w=x*y;}