about eng grammar

當然是call me back對，call back是phrasal verb
而phrasal verb可由（動詞＋副詞）或（動詞＋介詞）而組成
若由副詞組成的pharsal verb，其受詞置於副詞前後都可，如：
They pulled the old church down和They pulled down the old church皆可
但若受詞是”代名詞”，那麼受詞必須在副詞之前
如：pull it down就不可以說成pull down it

而由介詞組成的phrasal verb，則不論受詞是否代名詞，都要放在介詞之後，因為介詞是必須有受詞的，如：
You must look after your brothers 或please look after him.等皆不可說成
look your brothers after或look him after

call back正是由副詞組成的phrasal verb，而me是代名詞，故必須置於副詞back之前，因此，只有
call me back才對
希望幫到你！

Call me back is correct. There is no such thing as call back me.

2. call me back is correct

The 1st one doesn't make sense at all.
You can say simply say call back (please) without the me.
Or you can simply say call me without the back.

There isn't really an explanation, it just appears to be like that in the english language.

Call me back is the correct answer...

There isn't really an explanation...but you just won't say call back me...

another good example is:

lift me up(correct)
lift up me(incorrect)

bring it back(correct)
bring back it(incorrest)