下述“软骨母细胞瘤”诊断要点中,哪项不正确()
A.25岁以下多见
B.可恶变
C.好发于长管状骨骨骺区、干骺端
D.偶有骨膜反应
E.不侵犯关节
参考答案:E
下列物质,属于纯净物的是( )
A.可口可乐
B.无尘空气
C.氢氧化钙
D.含碘食盐
He turns deaf ear to his parents, ________ many times they have pointed out his weaknesses.[ ]
A. whatever
B. whichever
C. however
D. whenever