A.丙階段樹(shù)脂 B.甲階段樹(shù)脂 C.乙階段樹(shù)脂 D.丁階段樹(shù)脂
A.PC﹤P B.P﹥PC C.與PC無(wú)關(guān) D.PC≥P
A.806~2419 B.962~2885 C.4630~5556 D.2921~5882