单项选择题
A.isupper( B.'A'<=c<='Z' C.'A'<=c&&c<='Z' D.c<=('z'-32)&&('a'-32)<=c
A.741 B.963 C.852 D.875421
A.if(x>=0 y=sqrt(; else y=sqrt(-; B.y=sqrt( if(x<0)y=sqrt(-; C.if(x>=0) y=sqrt(; if(x<0)y=sqrt(-; D.y=sqrt(x>=0x:-;