A.—CO—NH— B.NH2—CO— C.—NO—CH— D.—CH—NO—
A.α-碳原子上連接-NH2 B.α-碳原子上連接-COOH C.α-碳原子上連接酮基 D.α-碳原子上連接-NH2和-COOH
A.20 B.8 C.12 D.6