Quick note: the word 'cabeça' in Portuguese and 'cabbage' in English are related. The word 'cabbage' originally comes from the Normand word 'caboche', meaning 'head', so in a way 'head of cabbage' means 'head of head'. :-)
Good question. I was wondering the same thing. I'm guessing that "machucar" means that something hurts something else (is an active verb), whereas "doer" is a passive verb (my head isn't hurting anything). As botas machucam = The boots hurt. The boots are hurting my feet. The boots themselves don't feel any pain.
Anyway, this is just a guess. I don't know for sure.
That's pretty much it; machucar implies action - usually physical, but not necessarily so; doer implies reaction - something hurts.
You just forgot to mention the reflexive use of "machucar" (Eu me machuquei - I hurt myself [past simple]); in this case you hurt yourself, but there's still an agent-patient relationship at work (Who/What did the subject hurt?) that's entirely missing from "doer".
Olá Luis. Thank you so much for your quick and very helpful response! Obrigada!!
That's actually the English text shown when you're asked to translate into Portuguese. I suggested "hurts so" for 'doi tanto', but it wasn't accepted.
But is that correct in English though? It sounds really strange to say just "hurts so" without the "much".
In the US you would never hear that expression used, but you would in a British film or book.
Well, so maybe Duolingo isn't that bad after all? ;-) I agree that "hurts so badly" or even "so much" is better, indeed! (I was just experimenting with Duolingo to see what the system would accept.)
Can tanto translate to "too much' or "so much"? It seems inconsistent and I lost a heart for "too much"
Well, I think it depends on the context and intonation. So it should also be accepted.
Why does 'tanto' come after the noun here while it's before the noun in "I like my mother so much"? ('Eu gosto tanto da minha mãe', I think was the sentence...or was it it 'gosto tanta da'?)
Could this be written in the same way, like "It hurts so much, my head"?
So I guess all that's left to ask about is the "tanto" in 'Eu gosto tanto da minha mãe'. Why doesn't "mãe" dictate that it's 'tanta' being used?
It would be "tanta" if it was related to the word "mãe", which is feminine. In this case, "tanto" is related to the verb, then it is always in its base form (masculine, singular)