单项选择题
A.4 B.5 C.6 D.7
A.DEBAFC B.DEFBCA C.DEBCFA D.DEBFCA
A.(10,50,80,30,60,20,15,18) B.(10,18,15,20,50,80,30,60) C.(10,15,18,50,80,30,60,20) D.(10,30,60,20,15,18,50,80)