下列sql语句运行结果是： select lpad('wjg',3,'-') from dual; select lpad('wjg',2) from dual; select rpad('wjg',5,'-') from dual; select rpad('wjg',2) from dual; A ---; wj; wjg--; wj; B ---; wj; wjg--; jg; C wjg; wj; wjg--; wj; D wjg; wj; wjg--; jg; 答案是c