A.5N級B.4N5級C.4N級D.3F級
A.3M級B.3D級C.3N級D.3F級
A.鈦的質(zhì)量分數(shù)不小于99.99%B.鈦的質(zhì)量分數(shù)不小于99.9%C.鈦的質(zhì)量分數(shù)不小于99.8%D.鈦的質(zhì)量分數(shù)不小于99%