A.O2.
B.NO2.
C.N2.
D.O3.

A.Zn.
B.Al.
C.Fe.
D.Mg.

A.Fe2(SO4)3.
B.Fe2O3.
C.Fe(OH)3.
D.FeO.

A.25
B.75
C.50
D.250

A.1080 gam.
B.432 gam.
C.1350 gam.
D.864 gam.

A.Ag.
B.Zn.
C.Cu.
D.Au.

A.1,344.00
B.0,896.
C.2,240.00
D.0,448.

A.focusing
B.breaking
C.imposing
D.judging

A.didn’t he
B.don't they
C.did they
D.didn't they

A.has been upgraded
B.is upgraded
C.have been upgraded
D.has upgraded