ryokou no mae ni, zyuudenkeeburu wo kaban ni ireta ka douka kakuninsimasu.

の links 旅行 and 前 so that 前 is specifically the time before the trip.

• 旅行 = trip, travel
• 前 = before, front
• 旅行の前 = before the trip

A good way to think of it is that の turns 旅行 into something like a modifier for 前.

Compare:

• 旅行の前に = before the trip
• 食事の前に = before the meal
• 授業の前に = before class

Without の, 旅行前 can exist in some contexts, but 旅行の前に is the more standard and beginner-friendly structure.

In this sentence, 前に means before in a time sense.

The に marks the time point relative to which the main action happens:

• 旅行の前に = before the trip
• then the main action: 確認します = check

So the structure is:

• [time expression] に + action

Examples:

• 寝る前に、歯を磨きます。 = Before sleeping, I brush my teeth.
• 出かける前に、鍵を確認します。 = Before going out, I check the keys.

Here, 前に is functioning as a set phrase meaning before doing / before something.

Because the speaker is checking whether the action of putting the cable in the bag already happened.

So the timeline is:

1. There is a trip coming up.
2. The speaker checks now.
3. What they are checking is whether they put the charging cable in the bag.

That is why the embedded clause is past:

• 入れたかどうか = whether I/they put it in

This is very natural in Japanese. The tense inside the かどうか clause reflects the event being checked, not the tense of the main verb.

Compare:

• 持っているかどうか確認します。 = I check whether I have it.
• 入れたかどうか確認します。 = I check whether I put it in.

かどうか means whether or not.

It is used when you are unsure about something and want to express whether X is true.

In this sentence:

• 入れたかどうか確認します
• = check whether or not I put it in

Structure:

• plain clause + かどうか + verb

Examples:

• 行くかどうか分かりません。 = I don’t know whether I’ll go.
• 好きかどうか聞きます。 = I’ll ask whether they like it.
• 忘れたかどうか確認します。 = I’ll check whether I forgot it.

Often, English learners first learn か for direct questions, but here it is not a direct question. It is part of an embedded whether clause.

That か marks the clause as a question-like idea inside a larger sentence.

• 入れた = put in
• 入れたか = did I put it in?
• 入れたかどうか = whether I put it in or not

So this か does not mean the speaker is directly asking someone aloud. Instead, it turns the clause into something that can be the object of verbs like:

• 確認する = check
• 分かる = know/understand
• 聞く = ask
• 決める = decide

You can think of it as forming an embedded yes/no question.

を marks the direct object of 入れた.

What was put into the bag?

• 充電ケーブルを = the charging cable

So:

• 充電ケーブルを かばんに 入れた
• = put the charging cable into the bag

This is the normal pattern:

• object を place に 入れる

Examples:

• 本をかばんに入れる。 = Put the book in the bag.
• 財布をポケットに入れる。 = Put the wallet in the pocket.

Because に marks the destination or target location of 入れる.

With 入れる, the thing goes into a place, so the place is marked by に:

• かばんに入れる = put into the bag

This is a very common pattern:

• 箱に入れる = put into a box
• 冷蔵庫に入れる = put into the refrigerator

So in this sentence:

• 充電ケーブルを = the thing being put in
• かばんに = the place it is being put into

Japanese often omits the subject when it is clear from context.

So even though English would often say something like I check whether I put the charging cable in my bag before the trip, Japanese can simply say:

• 旅行の前に、充電ケーブルをかばんに入れたかどうか確認します。

The omitted subject is usually understood from the situation. Depending on context, it could mean:

• I check whether I put it in
• he/she checks whether they put it in
• we check whether we put it in

This kind of omission is extremely common in natural Japanese.

確認します is the polite ます-form of 確認する.

Using ます makes the sentence polite and neutral, which is very common in textbook Japanese and everyday polite speech.

• 確認する = plain form
• 確認します = polite form

Both are grammatically correct; the difference is mainly politeness/register.

Compare:

• 旅行の前に、確認する。 = plain/casual
• 旅行の前に、確認します。 = polite

It most naturally means before the trip or before traveling, and in many situations the practical meaning is very similar.

However, grammatically:

• 旅行の前に is built from the noun 旅行
  • の前に
• so it is literally before the trip

If you specifically want before going on the trip as an action, you might also see forms like:

• 旅行に行く前に = before going on the trip
• 出発する前に = before departing

So 旅行の前に is slightly more noun-based, while 旅行に行く前に is more verb/action-based.

Both can be used, but they have slightly different flavor.

• かばん is a common native/Japanese-style everyday word
• バッグ is a loanword from English bag

In many contexts they overlap. But depending on the type of bag and the speaker’s preference, one may sound more natural than the other.

For a general learner sentence, かばん is very standard and easy.

Examples:

• かばんに入れる = put it in the bag
• バッグに入れる = put it in the bag

Both are understandable.

No, normal Japanese writing usually does not use spaces like this.

This:

• 旅行　の　前　に、　充電ケーブル　を　かばん　に　入れた　か　どうか　確認します。

is spaced out to help learners see the parts more clearly.

In normal writing, it would usually be:

• 旅行の前に、充電ケーブルをかばんに入れたかどうか確認します。

Japanese relies on:

• kanji
• hiragana
• katakana
• punctuation

rather than spaces, to make sentence structure readable.