mousikomisyo ni namae to zyuusyo wo teinei ni kaite kara, madoguti ni dasimasita.

Because 申込書に書く means to write on the application form.

Here, 申込書 is the place/surface where the writing goes, so に marks that target location.
The thing actually being written is 名前と住所, so that takes を.

• 申込書に = on the application form
• 名前と住所を = name and address

So the structure is:

• X に Y を 書く = write Y on/onto X

Example:

• ノートに名前を書く = write your name in the notebook

Because 名前と住所 is one combined object: name and address.

Japanese often lists multiple nouns with と, and then marks the whole list with one particle.

So:

• 名前と住所を = name and address (as the thing being written)

You do not need:

• 名前をと住所を ❌

That would sound unnatural here.

丁寧 is a na-adjective, and when a na-adjective is used adverbially, it usually becomes 〜に.

So:

• 丁寧な字 = neat/polite writing
• 丁寧に書く = write carefully / neatly / politely

In this sentence, 丁寧に describes how the person wrote.

So the nuance is something like:

• carefully
• neatly
• properly

It is not just about being “polite” in a social sense. Here it more naturally means carefully and neatly.

〜てから means after doing ....

So:

• 書いてから = after writing

It shows that one action happened first, and then the next action happened afterward.

Sequence here:

1. 申込書に名前と住所を丁寧に書いて
2. から
3. 窓口に出しました

So the sentence means the application was submitted after the writing was completed.

This is a very common grammar pattern:

• 食べてから行く = go after eating
• 宿題をしてから寝る = sleep after doing homework

Yes, it could, but the nuance changes slightly.

• 書いて、窓口に出しました。 = I wrote it and submitted it at the counter.
• 書いてから、窓口に出しました。 = After writing it, I submitted it at the counter.

Both show sequence, but 〜てから makes the order more explicit. It emphasizes that the second action happened only after the first one was done.

So から adds a clearer sense of first this, then that.

Yes, 出す has many meanings, and submit/hand in is one of them.

In this context, 書類を出す or 申込書を出す means:

• submit a document
• hand in a form
• present paperwork

So 窓口に出しました means something like:

• submitted it at the counter
• handed it in at the service window

This is a very common extended meaning of 出す in Japanese.

Other examples:

• 宿題を出す = hand in homework
• 履歴書を出す = submit a résumé
• 申請を出す = file an application

Here, 窓口に出す means to submit something to the counter/service window.

The に marks the destination or target of the action: where the form is being handed.

So:

• 窓口に = to the counter / at the service window
• 出しました = submitted / handed in

You can think of it as:

• handing the form to the counter staff
• submitting it at the service window

In English, we might translate this more naturally as at the counter, but Japanese uses に because it treats 窓口 as the target point of submission.

窓口 literally means window, but in everyday Japanese it often means a service counter, reception desk, or office window where you deal with staff.

In places like:

• banks
• post offices
• city halls
• stations
• offices

窓口 usually refers to the place where you go to submit forms, ask questions, or receive service.

So in this sentence, it is best understood as:

• the service counter
• the reception window
• the application desk

Because Japanese often omits subjects when they are clear from context.

Even though English usually needs something like I, Japanese often leaves it out if the listener can understand it.

So this sentence naturally implies something like:

• (私は) 申込書に名前と住所を丁寧に書いてから、窓口に出しました。

The omitted subject is probably I, but it could also be understood more generally depending on context.

This is one of the most common features of natural Japanese.

Yes. The first part sets up the action that happened before the main action.

The main action is:

• 窓口に出しました = submitted it at the counter

Everything before から explains what happened first:

• 申込書に名前と住所を丁寧に書いてから = after carefully writing my name and address on the application form

So the sentence structure is:

• [first action] + てから + [main action]

This is a very standard way to connect two actions in order.

出しました is:

• past tense
• polite style (ます-form)

Dictionary form:

• 出す

Polite non-past:

• 出します

Polite past:

• 出しました

So the speaker is speaking politely and describing a completed action in the past.

Also notice that the earlier verb is in て-form:

• 書いて

That is because it is part of the connective pattern 〜てから, not because it is present tense.

Grammatically, yes, 丁寧に often means politely. But in this sentence, the more natural interpretation is carefully/neatly.

That is because the verb is 書く and the object is 名前と住所 on a form. In that context, 丁寧に書く usually means:

• write carefully
• write neatly
• fill it out properly

If the sentence were about speaking, then 丁寧に would more naturally mean politely:

• 丁寧に説明する = explain politely
• 丁寧に話す = speak politely

So the exact nuance depends on the verb and context.