∵f(x)=sin2x-
cos2x
3
=2(
sin2x-1 2
cos2x)
3
2
=2sin(2x-
),π 3
将函数f(x)=sin2x?
cos2x的图象向左平移m(m>0)个单位
3
得到f(x+m)=2sin[2(x+m)-
]=2sin(2x+2m-π 3
),π 3
∵g(x)=f(x+m)=2sin(2x+2m-
)为偶函数,π 3
∴2m-
=kπ+π 3
,k∈Z,π 2
∴m=
+kπ 2
,k∈Z,5π 12
又m>0,
∴mmin=
.5π 12
故选:D.