ryokou no mae ni, razio no kandenti mo mite oita hou ga ii.

Each の is linking two nouns.

• 旅行の前 = before the trip

  • 旅行 = trip
  • 前 = before / front
  • together: the time before the trip

• ラジオの乾電池 = the radio’s batteries or more naturally the batteries for the radio

  • ラジオ = radio
  • 乾電池 = dry-cell batteries

So here, の is doing the very common job of connecting nouns, similar to of, for, or an apostrophe-s depending on context.

前に means before.

In this sentence:

• 旅行の前に = before the trip

The pattern is:

• Noun + の + 前に = before a noun
  
  • 食事の前に = before the meal
  • 寝る前に = before sleeping

Here, 前 is a noun, and に marks the time point.

The comma is there because 旅行の前に sets up the time frame first: Before the trip, ...

Japanese often uses a comma after a time phrase at the beginning of a sentence to make it easier to read. It is not always absolutely required, but it is very natural here.

も means also or too.

So ラジオの乾電池も suggests that the batteries are another thing you should check, in addition to something else already being discussed.

For example, the speaker may have already mentioned checking luggage, tickets, or the radio itself, and now adds:

• the batteries too

Without も, it would sound more like simply check the radio batteries. With も, it has the nuance of check the radio batteries as well.

Yes, 見る basically means to see / to look, but in many contexts it also means to check / examine / inspect.

So 乾電池を見ておく does not mean just look at the batteries with your eyes. It means something like:

• check the batteries
• make sure they are okay
• inspect whether they still have power

This is a very common extension of 見る in Japanese.

見ておく is 見る in the -ておく form.

The pattern 〜ておく means:

• do something in advance
• do something beforehand
• do something and leave it done for later convenience

So:

• 見る = to look / check
• 見ておく = to check in advance

In this sentence, it means checking the batteries ahead of time before the trip.

Because the sentence uses the pattern:

• 〜ておいたほうがいい

This is a very common way to say:

• it would be better to do X in advance
• you should probably do X beforehand

Even though おいた is past tense, the whole expression is not talking about a past event. It is part of a set grammar pattern for advice.

So:

• 見ておいたほうがいい = it would be better to check them in advance

This is one of those cases where the literal tense does not match a direct English tense.

〜たほうがいい means:

• had better
• it would be better to
• should

It is used to give advice or recommendations.

Examples:

• 早く寝たほうがいい。 = You should go to bed early.
• 薬を飲んだほうがいい。 = You should take medicine.

So:

• 見ておいたほうがいい = You should check them beforehand.

This is advice, not a strict command.

Yes.

• 見たほうがいい = you should check / you’d better look
• 見ておいたほうがいい = you should check in advance / beforehand

The おく adds the nuance of preparation. Since the sentence is about before a trip, that extra nuance is very important.

So 見ておいたほうがいい sounds more like:

• make sure you check them ahead of time so you are prepared

In full form, you might expect:

• ラジオの乾電池を見ておいたほうがいい

That would be perfectly natural.

But when も is used, it often replaces particles like を, が, or は.

So:

• 乾電池を
  • も does not usually become 乾電池をも in everyday speech here
• instead it becomes 乾電池も

So も is functioning as the particle for that noun phrase.

Japanese often leaves the subject unstated when it is clear from context.

So this sentence does not explicitly say:

• you should check
• we should check
• someone should check

But in ordinary use, 〜たほうがいい usually implies advice to the listener, so the natural interpretation is:

• You should check the radio batteries too before the trip.

By itself, it most naturally means the radio’s batteries or the batteries for the radio. In context, it usually suggests checking whether the radio’s batteries are still good.

Depending on the situation, that could mean:

• the batteries currently in the radio
• the batteries you plan to bring for it

The sentence itself does not force one specific interpretation. It just says the batteries related to the radio should be checked.

乾電池 means dry-cell battery, which is a common everyday battery type. 電池 is the more general word for battery.

So:

• 電池 = battery (general)
• 乾電池 = dry battery / disposable-style battery

Using 乾電池 is a bit more specific. It makes sense for something like a portable radio.

It is natural and practical. It sounds like everyday advice before traveling.

The nuance is something like:

• Before the trip, you should check the radio batteries too.

Key feelings in the sentence:

• 旅行の前に = before the trip
• も = too / also
• 見ておいたほうがいい = should check in advance

So the full sentence has a helpful, preparatory tone.