for those terms with no g, you can use ∂A∂B = ∂(A∂B) - A∂∂B,then you can find the second term εμναβ∂∂ should be zero.
for terms with g, you need ∂(ABC) = ∂ABC+A∂BC+AB∂C, and combining them with εμναβ fabc, you will see the right hand three terms are equivalent with each other, that's why you...