hoteru no uketuke de yoyakubangou wo misetara, sugu heya no kagi wo moraemasita.

で marks the place where an action happens.

So in ホテルの受付で, the action of showing the reservation number happens at the hotel reception/front desk.

• ホテルの受付で = at the hotel reception
• If you used に here, it would sound more like a destination or point of existence, not the place where the action is carried out.

So で is the natural particle because this is the location of the action.

受付 means reception, front desk, or check-in counter, depending on context.

In a hotel sentence like this, ホテルの受付 most naturally means:

• the hotel front desk
• the reception desk

It does not mean the receptionist as a person here. It refers to the place/service counter.

の connects nouns. It often works like of, but in natural English it is often translated more smoothly.

• ホテルの受付 = the hotel’s reception / the hotel front desk
• 部屋の鍵 = the room’s key / the room key

So の shows the relationship between the two nouns.

A useful way to think about it:

• A の B = B related to A

Here:

• the reception related to the hotel
• the key related to the room

In this sentence, たら means something like:

• when
• after
• once

So 予約番号を見せたら means:

• when I showed my reservation number
• after showing my reservation number

It connects the first action to what happened next.

In this sentence, it gives the sequence:

1. showed the reservation number
2. then got the room key

So たら is not always a strict conditional like if. Very often, especially in past-tense storytelling, it means when/after doing X, Y happened.

Because 見せる means to show, while 見る means to see/look.

• 見る → 見たら = when I saw...
• 見せる → 見せたら = when I showed...

Here, the speaker is showing the reservation number to the front desk, so 見せる is the correct verb.

を marks the direct object of the verb.

The thing being shown is 予約番号:

• 予約番号を見せる = to show the reservation number

So を tells you what was shown.

Japanese often leaves out subjects when they are obvious from context.

Here, the sentence is naturally understood as something like:

• I showed the reservation number
• I got the room key

Because it is clear from the situation, Japanese does not need to say 私は.

This is very normal. In fact, adding 私は could sound unnecessary unless you are contrasting yourself with someone else or emphasizing the subject.

すぐ means:

• right away
• immediately
• soon

In this sentence, it modifies the second action:

• 部屋の鍵をもらえました = was able to receive the room key
• すぐ部屋の鍵をもらえました = was able to receive the room key right away

Its placement before what it modifies is very natural in Japanese.

もらえました is the potential form of もらう in polite past:

• もらう = to receive
• もらえる = can receive / be able to receive
• もらえました = was able to receive

In real usage, もらえました often sounds a little softer or more natural in situations where something became available to you.

So this sentence suggests:

• I was able to get the room key
• They gave me the room key

By contrast:

• もらいました = I received it
• もらえました = I was able to receive it / I got it successfully

Both can work, but もらえました can carry a slight nuance that things went smoothly or as hoped.

Not in exactly the same structure.

• もらう focuses on the receiver: I received
• くれる focuses on the giver giving to me: they gave me

So:

• 部屋の鍵をもらえました = I was able to receive the room key
• 部屋の鍵をくれました would be unnatural as written, because くれる normally needs the giver as the subject.

A more complete sentence with くれる would be:

• 受付の人が部屋の鍵をくれました。
• The receptionist gave me the room key.

The original sentence keeps the focus on the speaker’s experience, so もらえました fits well.

Adding 部屋の makes it specific.

• 鍵 = key
• 部屋の鍵 = room key

At a hotel, just saying 鍵 might still be understood, but 部屋の鍵 is clearer and more precise. It tells you exactly which key was received.

Yes, 予約番号 is a compound noun.

It is made from:

• 予約 = reservation
• 番号 = number

Together, they form 予約番号 = reservation number

Japanese often combines nouns directly into compound words, so you do not always need の.

Compare:

• ホテルの受付: a looser noun connection using の
• 予約番号: a fixed compound noun

Both patterns are common in Japanese.

It is grammatically a conditional form, but in this sentence it is functioning more like a time-sequence marker: when/after.

So although たら can mean if, here the meaning is more like:

• when I showed it, then...
• after I showed it, ... happened

This is a very common use of たら in past events.

Not completely. Japanese word order is more flexible than English, as long as the particles make the roles clear.

For example, the original:

• ホテルの受付で予約番号を見せたら、すぐ部屋の鍵をもらえました。

You could also move すぐ slightly:

• ホテルの受付で予約番号を見せたら、部屋の鍵をすぐもらえました。

The original sounds very natural, though. In Japanese, the most important thing is often that the verb comes near the end and the particles clearly mark each part.

No, standard Japanese normally does not use spaces between words.

The natural written form is:

ホテルの受付で予約番号を見せたら、すぐ部屋の鍵をもらえました。

Spaces are often added only in teaching materials to help learners see the word boundaries more easily.

So the spaced version is useful for study, but it is not normal everyday writing.