"It will snow this evening."
(i'm american) i dont understand all the words like "subject" and "main pupil" or whatever, however...
thing that is affected by verb を / が
as far as why duo is teaching you to say "今日、"; In spoken language, they speak 'incorrectly,' the same way we do, and it eventually becomes 'correct.' So, in this case, when you're saying the time, you don't always have to say は。
as far as が or を、Here's a paraphrase. In short, having the focus spread throughout the entire sentence, or focusing only directly on one thing
In the が + potential construction, the focus is on the noun.
新聞が読める (what I am able to read is newspapers [as opposed to other written media])
ここで切符が買えますか (is this where tickets [as opposed to other items for sale] can be bought?)
In the を + potential construction, the focus is on the entire phrase.
新聞を読める (what I am able to do is read newspapers)
ここで切符を買えますか (is this where I am able to buy tickets [as opposed to doing some other action]?)
を + potential is not yet considered standard, but has begun to gain acceptance among some speakers.
(Paraphrased from Japanese: The Spoken Language)
-to answer your question, the most proper answer is
^ im confused on that too. When you say Konbanwa it means "good evening" but I would imagine you'd be saying it while its already evening similar to saying good morning. So if evening is a time of day you can be in, why is evening supposed to be some expression of the future, or can it be both?