14.Tom’s elder sister is only one year ___ than he.

A．elder

B．older

C．more elder

D．more older

咀嚼时，牙齿磨耗明显的部位是（）

A.上颌磨牙颊尖

B.下颌磨牙颊尖

C.上颌磨牙颊轴嵴

D.下颌磨牙颊轴嵴

E.上、下颌磨牙咬合面发育沟