5、C.couldn'tD.wasn'tableto14.______Igobackbeforelunch? No,Idon'tthinkyou________.A.Need...mustB.Do...needtoC.Must...havetoD.May....oughtto15.Theteacherdoalltheexercises,butapupil_______.A.needn't....mustB.maynot...must C.needn't....needn'tD.can't....must16.Wouldyouopenthewindowplease? Ye