を vs. で in these examples

Hello everyone,

Every time I think I have a clear grasp of で, I get thrown for a loop.  I have an every-growing list of the differences between で and に, but I seem to be not understanding clearly the difference sometimes between using で vs. を

Could you speak in English for me?
英語で話してもらっても良いですか / Ēgo de hanashite moratte mo ii desu ka
Could you write in romaji for me?
ローマじでかいてもらってもいいですか / Rōmaji de kaite moratte mo ii desu ka?

vs.

I speak Japanese
私は日本語を話します / nihongo wo hanashite
Could you close the window for me?
まどをしめてもらってもいいですか / Mado wo shimete moratte mo ii desu ka

When I go over my nightly reviews, I keep using を in the first two examples, and I think that's because I don't understand why で is used.  At first I thought that it was because an action was being taken and it was in the te form.  But that wouldn't make sense based on  を in "まどをしめて" 

I don't understand why the action of writing and speaking a language uses a different particle to the action of closing a window. Could someone please enlighten me on my confusion between using を vs. で in these examples?  Is it because the window is a physical object, vs. a language is not?  But if that's the case, then "nihongo wo hanashite" should also use で.

Thank you so much!

Hi there, I just saw this post. で is the particle used for the method, manner, medium or "tool/instrument"  with which something is done. を is the particle used to mark the object of the (transitive) verb.

So in the first example, "Could you speak English for me?", "(for) me" is the object complement, while "(in) English" is the "language medium" in which you would like to be spoken to , so it's で。

The second example is similar in that rōmaji is the "medium of writing".

Ex:
鉛筆 (えんぴつ)で　用紙 (ようし)を　書き込んで (かきこんで)　下さい (ください)。
Please fill out the form in pencil.

In this case, the form is the object complement (fill what?), while (in) pencil is the  "tool/manner" of filling, so it gets で。

鉛筆 (えんぴつ) - pencil
用紙 (ようし) - form
書き込む (かきこむ) - to fill out (a form), 書き込んで is the て-form (the て-form is used because it's being connected to another verb, 下さる (くださる) (to give).
 

Thank you very much - that was very helpful and explained so nicely!

こんにちは (Konnichiwa) イ リ ニ  and toru e,

Thank you for your question! 

As toru e says, で (de) can be used to show a means and を (o) can be used to mark an object. 

We have recently released brand new Language and Culture lessons for level 1 Japanese that explain in-depth some of the other ways you can use を (o) and で (de) and how they are different.

Here's the links to a couple lessons you might find helpful!

The particle を (o)
https://members.rocketlanguages.com/members/japanese/lessons/5044/2-6-making-sentences-with-verbs

The particle で (de)
https://members.rocketlanguages.com/members/japanese/lessons/5071/3-8-All-About-Location

I hope this helped! Please let me know if you have any more questions.

べんきょう　を　がんばって　ください！ (Benkyō o ganbatte kudasai!)