判断题
A.a[i] = ‘\0’ B.a[i] != ‘\0’ C.b[j] = ‘\0’ D.b[j] != ‘\0’
A.c[k] = a[i]; i++; B.c[k] = b[j]; i++; C.c[k] = a[i]; j++; D.c[k] = b[j]; j++;