The big trouble is we know these sentences are often general, so they don't need the article in English. Nine times out of ten if we leave it out, the owl goes "oops, that's wrong" you missed a word. One tires of reporting it. When you do reluctantly put the article in (to avoid wasting time going over the exercise again), that's the time the owl insists on the general sense and crosses out your "the".
- "in this sentence it sounds like you're speaking of babies in general since you're using the Present Tense. If you were talking in specific, you'd probably say "Os bebês estão crescendo rápido" (Gerund)."
The problem is that the Portuguese sentence might be speaking in general, but the English translation is specific (The babies grow fast)
Babies grow fast (in general)
The babies grow fast (specific)
Actually no, since babies here are general, not specific. The same way you say "carrots are vegetables".
I think in BP you can omit "Os", but in this sentence it sounds like you're speaking of babies in general since you're using the Present Tense. If you were talking in specific, you'd probably say "Os bebês estão crescendo rápido" (Gerund).
Asssim como o colega TiagoMoita_PT [https://www.duolingo.com/TiagoMoita_PT] explicitou, "Os bebês crescem rápido" é mais específico que "Bebês crescem rápido".
Imagine a cena de um berçário, ou de uma família com trigêmeos, você poderia dizer a eles: "Os bebês crescem rápido", ou seja, os bebês do berçário/filhos trigêmeos crescem rápido, já a frase "Bebês crescem rápido" é mais geral, genérica.
All good, but I just got marked wrong for not having the word "up" in my translation. How to tell the difference between "growing" and "growing up"??
I don't think there is a difference as concerns babies. Someone else might disagree though.
It sounds more natural for me to say "Babies grow up fast"
Also, I'm still confused: Os bebês crescem rápido" é mais específico que "Bebês crescem rápido".
Thus "Os bebês crescem rápido" = The babies grow up fast.
Bebês crescem rápido = Babies grow up fast.
That is not what I see on this page.