Why "Él ha enviado el vestido" is incorrect?
It is not. The sentence here is three days old; give it some time. :)
I known the 'él' is not necessary - but we really shouldn't be marked incorrect for putting it in.
I put the same thing and was marked wrong. Seems like an error on Duolingo’s part.
agree that although el is optional it is not incorrect to include it
"El ha mando el vestido "was marked wrong too , in both cases the El should be correct since "Ha " could mean he or she so without it we have no idea who sent the dress
Martyn, there's a syllable missing in your mandado. Mando is just the present-tense yo form.