whAt DoEs thE spEAkEr mEAn A、mAry sings thE BEst in hEr grADE.B、thE spEAkEr hAs no iDEA whEthEr mAry sings wEll.C、mAry’s singing skills ArE inFErior to A lot oF hEr ClAssmAtEs.D、mAry’s singing skills rAnk thE sEConD in hEr ClAss.