Translation:I have been opening the windows whenever I can.
There's a problem here nonetheless, as the present perfect continuous is being used in the first clause, and that implies continuation, whereas the second clause's "whenever I can" implies there are singular points in time and no continuation.
"I've been opening the windows for a long time" would definitely be a correct way to use this.
Another would be:
"I've opened the windows whenever I've been able to (do so)'.
It's just an awkward sentence and I don't have the skill in Portuguese to conclude whether or not it's also got issues in that language.
"Whenever I can" means "each and every time", not "a singular point of time".
I’m embarrassed whenever I think about it.
I try to let the kids out to play whenever possible.
There is an action: "the window is being opened as often as I can [manage it.]" (passive voice). The present perfect progressive form can imply an unfinished activity. This link is helpful:
We often use adverbs of frequency like sometimes, always and never with the present simple:
Does it mean that here "whenever" is not adverb of frequency ?
Summarizing, could you please advise if the sentence " I open the windows whenever I can " is incorrect?
We should not translate one language to another directly. For me English meaning is some habbit, what I do every single day.
The dictionary defines it as "every or any time", which means every (singular) time or any (singular) time. It regards non-specific singular points in time, it doesn't regard continuation.
That's why it's better to say "I've been opening windows whenever I've been able to" or "I've been opening the windows all my life".
'I've been opening the windows every time I can' doesn't sound right at all, and that's what 'whenever' accounts for.
The only thing that's wrong (in my opinion) is when this is combined with "I had been..." I think there is to be a match between the verb tenses used in the sentence; Either it is "I have been opening the windows whenever/as often as I can" or it is "I had been opening the windows whenever/as often as I could". This is a discussion going on elsewhere -- Duo has a general problem matching the verb tenses across the different parts of sentences.
DL's sentence uses the "present perfect progressive" tense to refer to a situation that started in the past and continues until the moment of speaking.
Reread the link. The present perfect progressive has two interpretations which leave the sentence ambiguous. If in a telephone conversation I say that it's been snowing all week, there is no way that the person on the other end of the line knows whether it is still snowing or whether the snow has recently stopped and its effects (icy roads, snow drifts) are still with us. The language is flexible and depends on context despite the rigid translations required by DL.
Is it actually usual to use the present tense ("sempre que eu posso") in a sentence starting with pretérito perfeito composto in Portuguese? And is it also possible to use one of the past tenses ("sempre que eu podia/pude")? And, if yes, what's most common in formal as well as in informal contexts? Thanks in advance for clarifying! :)
Thank you very much for your feedback. I discovered very quickly how Duolingo wants me to treat the "pretérito perfeito composto" because it would not allow me another approach... Overall, I think that this particular Duolingo course is one of the most difficult with respect to the complexity of sentences. I know both languages well enough that I normally can pass the unit test without or very few errors, but this one is quite a challenge.