muryousyuuri ni tuite tenin ni kikimasita.

無料修理 is a noun phrase made from two parts:

• 無料 = free of charge
• 修理 = repair

Together, 無料修理 means free repair or repair at no charge.

Japanese often combines nouns this way, so something that would take multiple words in English can appear as one compact expression in Japanese.

について means about, regarding, or concerning.

So:

• 無料修理について = about the free repair

It attaches to a noun and shows the topic or subject matter of what follows.

Examples:

• 日本の文化について勉強します。 = I study about Japanese culture.
• 仕事について話しました。 = I talked about work.

In your sentence, it tells us what the speaker asked about.

They are doing two different jobs.

1. について

   • This is a set expression meaning about
   • The に here is part of that grammar pattern

2. 店員に

   • This に marks the person the speaker asked
   • With 聞く, the person you ask is often marked by に

So in:

• 無料修理について = about the free repair
• 店員に = to the store clerk / from the store clerk

Even though both contain に, they are not the same grammatical role.

With the verb 聞く when it means to ask, the person you ask is usually marked with に.

So:

• 店員に聞きました = asked the store clerk

A very common pattern is:

• 人に ことを 聞く
• ask a person something

For example:

• 先生に質問を聞きました would sound unnatural, because with 聞く, the thing asked is not usually phrased that way in modern standard Japanese. More natural is:
  • 先生に質問しました = I asked the teacher a question
  • 先生にそのことを聞きました = I asked the teacher about that

In your sentence, the content being asked about is shown by について, so 店員に is the person being asked.

The dictionary form is 聞く.

Here is the breakdown:

• 聞く = to hear / to listen / to ask
• 聞きます = polite non-past
• 聞きました = polite past

So 聞きました means asked, heard, or listened, depending on context.
In this sentence, because of 店員に and 無料修理について, it clearly means asked.

That is just how this Japanese verb works. 聞く has a wider range than any single English verb.

It can mean:

• to hear
• to listen
• to ask

The meaning comes from context.

Examples:

• 音楽を聞きます。 = I listen to music.
• 話を聞きました。 = I heard/listened to the story.
• 先生に聞きました。 = I asked the teacher.

So in your sentence, the presence of 店員に makes ask the natural meaning.

Because Japanese normally places the main verb at the end.

So the structure here is roughly:

• 無料修理について = about the free repair
• 店員に = to the store clerk
• 聞きました = asked

A very natural English rearrangement is:

• I asked the store clerk about the free repair.

Japanese and English often organize information differently, but the verb-final pattern is very standard in Japanese.

No, the subject is omitted.

Japanese often leaves out subjects when they are obvious from context. So the sentence does not literally include I, but it is usually understood as:

• I asked the store clerk about the free repair.

Depending on context, it could theoretically be he/she/they asked, but in isolation learners are often shown I asked as the default interpretation.

Yes, it is a complete and natural sentence.

Japanese does not always need a visible topic marker like は if the sentence already makes sense in context.

Also, there is no を here because the content of the question is being expressed with について instead:

• 無料修理について = about the free repair

So the sentence is complete as it is.

A fuller version could be:

• 私は無料修理について店員に聞きました。
  • As for me, I asked the store clerk about the free repair.

But the shorter version is very normal.

Yes. A few natural alternatives are:

• 無料修理のことを店員に聞きました。

  • I asked the store clerk about the free repair.

• 店員に無料修理について聞きました。

  • Same meaning, just a different word order

Both are natural. The original sentence is also natural.

A small nuance:

• 〜について sounds a little more formal or structured
• 〜のこと can feel a bit more casual and conversational

The word order is somewhat flexible.

So both of these are natural:

• 無料修理について店員に聞きました。
• 店員に無料修理について聞きました。

Both mean the same thing: I asked the store clerk about the free repair.

However, the information placed earlier can feel slightly more prominent. In the original sentence, 無料修理について comes first, so the topic of the question is introduced before the person being asked.

店員 means store employee, shop clerk, or store attendant.

It is a general word for someone working at a shop or store. Depending on context, English translations may vary:

• store clerk
• shop assistant
• sales clerk
• employee

So 店員に聞きました means the speaker asked a person working at the store.

Yes. 聞きました is polite past tense, so it normally means the asking happened in the past as a completed action.

So the sentence gives the sense:

• I asked
• not I ask
• not I am asking

If you wanted present/future polite, it would be:

• 聞きます = ask / will ask

Example:

• 無料修理について店員に聞きます。
  • I will ask the store clerk about the free repair.