Questions about できる and the potential form


I know that the potential form can take either が or を depending on the
volition degree when it comes to godan and ichidan verbs

漢字を読める (high volition) or 漢字が読める (low volition)

My question is regarding the case when there is a noun followed by a
漢語名詞/する動詞. Is it correct to say `英語が勉強できる`？ I am asking this because most
examples online are using godan verbs like the previous example which I
already know. Online, I would probably find a `英語を学べる`. I always catch myself
using a normal verb because of not being so sure about this grammar point.

I also know that I can use the `名詞＋が＋できる` pattern as in `日本語ができる`, but does it
mean that saying `英語が勉強ができる` is grammatically correct?

By the same logic, is it grammatically correct to say `英語を勉強をするのが好き`？

I came back to genki 2 after not finding a proper answer on 日本語文法辞典, and they
say that using できる with を is a substandard use. That is a ambiguous. Does it
mean sometimes people use it? Does it depend on the formality level of the
conversation?

I also noticed that everytime I think of saying `名詞＋漢語名詞` in the potential
form, I tend to say `名詞＋を+漢語名詞+できる`

Example: `英語を勉強できる`

Is it a real tendency I absorbed with immersion or is it a language bad habit?

A similar question has already been made but was not answered properly [What
is the difference between が（suru-verb）できる and を（suru-
verb）できる?](https://japanese.stackexchange.com/questions/95002/what-is-the-
difference-between-%E3%81%8C-suru-
verb-%E3%81%A7%E3%81%8D%E3%82%8B-and-%E3%82%92-suru-
verb-%E3%81%A7%E3%81%8D%E3%82%8B)




> Is it correct to say 英語が勉強できる？

Yes. 勉強できる works just like a potential verb 読める here. And here you can use
英語を, too.

> is it grammatically correct to say 英語を勉強をするのが好き？

No. You can say 英語を **勉強する** のが好き (without を).

> saying 英語が勉強ができる is grammatically correct?

No. In this case, できる alone is like a potential verb and can take **only one**
Noun+が. In this sense 勉強できる and 勉強ができる are different. The former can take
another が-phrase but the latter not (taken already by 勉強が).

So 英語ができる or 勉強ができる is fine, but 英語が勉強が is not.

> 英語を勉強できる

It is fine. My impression is 英語が勉強できる may be (slightly) more common though it
may depend on words as well.

