This sentence is pretty much nonsense: no one (in the UK, at any rate) would say "I finish the cake by dinner"; if the sentence read "...by dinner time", I'd have understood immediately. Ironically, though, oddities like this are very memorable! NB, the following is from the Collins Italian dictionary: 'entro febbraio' = ' by the end of February'.
This seems to me a very clumsy use of the word "by" because it is not really very clear in it's meaning. "Entro" in German "innerhalb" in English "within" would translate "I finish the cake within dinner", which signals that someone finishes the cake in the time dinner might take. The word "by" says rather than "within" "before" dinner. To give an example: "by the time (or before) I got there, the train had left". Of course I know that languages are not always totally interchangeable and therefore I would wish that DUO took this in consideration and gave examples which express the Italian usage of a word or a phrase more clearly.
I think TiagoMoita_PT is right. I have been told that it is normal to use the present for the near (or certain) future, while one who expresses a future action in future tense is indicating that he might and might not get around to it. "Finisco la torta entro cena." might respond to a question like 'Did you make the cake yet?'
Because entro does not mean "at". Here's the definition in un dizionario Italiano , and I hope this resource and its Inglese friend save you from asking "why not?" ever again. https://dizionari.repubblica.it/Italiano/E/entro.html
Thanks, but in my limited knowlegde of English the meaning is not exactly the same to the Italian phrase. By dinner means when the dinner actually starts, but here I think it means to finish the cake before dinner actually starts. Just confused. Sorry for asking trivial questions.
I thought 'entro" meant 'during'. I finish the cake during dinner. 'During" and 'by' are different time placements. I think both must be correct and would depend on what actually happened. Also I think the person was eating the cake during dinner, not jumping up to finish making the cake. If you wanted to say 'I finish the cake by dinner' , wouldn't you just admit it and say ' Finisco la torta prima di cenare'? I'm sure 'entro' must be fine as 'by' but I always see 'during' when I see 'entro'. Entro, dentro andiamo in centro Non si fina prima di cento passeggiare e cantare Dio, io, amo il mare.
This translation is simply wrong and needs to be changed. According to the Italian dictionary on the website of La Repubblica (thanks @malcolmissimo), entro means prima della fine di - by the end of. So here it means "by the end of dinner" - before dinner ends. Idiomatically: during. This is a bit tricky for an English learner because entro suggests "before dinner enters, i.e. before the start of dinner - which may be why there is so much confusion.
Finished is the past tense. The italian verb is the present tense, so you need finish (or "am finishing").
"Finish off" is commonly used colloquial English. It has overtones of (a) finishing the final remnants of something and/or (b) finishing something quickly and definitively. I would have thought there was a specific Italian expression for this. Native speakers please comment!
You may also come across "polish off", which is interchangable. It derives from the final cleaning of a piece of woodwork or metalwork, but is colloquially applied to anything
The Collins dictionary does not mention "during" anywhere. It gives several examples of both "within" and "by". In all cases the sense is effectively <in the time between now and> <time word or phrase>.
If this is accurate - and Collins normally is - then the problem is in the translation to English. It has got to be "dinner time" (or dinnertime, which is a correct abbreviation). Perhaps "cena" does carry the sense of a time?