A、0.6 B、0.8 C、1.1 D、1.2
A、R1>R2>R3 B、R1<R2<R3 C、R2>R3>R1 D、R1>R3>R2
A.H2/Raney B.Fe/HCl C.Zn-Hg/HCl D.保險(xiǎn)粉