若a、b、c1、c2、x、y均是整型变量，以下正确的swich语句是A:swich(a+b): { case 1: y = a+b; break; case 0: y = a-b; break; } B:switch(aa+bb): { case 3: case 1: y = a+b; break; case 3: y = b-a; break; } C:switch(a): { case c1: y = a-b; break; case c2: x = ad; break; default: x = a+b; } D:switch(a-b): { default: y = ab; break; case 3: case 4: x = a+b; break; case 10: case 11: y = a-b; break; } 答案: switch(a-b): { default: y = a*b; break; case 3: case 4: x = a+b; break; case 10: case 11: y = a-b; break; }