kouzyou wo kengakusita toki ha, hizyouguti to herumetto no basyo wo kakuninsimasita.

Because with とき, the tense of the verb before it shows whether that action happened before or after the main action.

• 見学したとき = when/at the time I toured it
• 見学するとき = when/about to tour it or when touring it

So 工場を見学したときは means the checking happened at the time of, or during/after, the factory visit.

見学する means to inspect, to observe, or to tour something for learning purposes. It is often used for places like:

• 工場を見学する = tour a factory
• 学校を見学する = visit a school to observe it
• 博物館を見学する = tour a museum

By contrast, 見る just means to see/watch/look at and is much more general.
So 見学する is more natural here because the sentence is about a formal or purposeful visit to a factory.

In 工場を見学した, 工場 is the direct object of 見学した.

So:

• 工場 = factory
• を = marks what is being toured/observed
• 見学した = toured/observed

Together: toured the factory.

The は marks the time phrase as the topic or frame for the rest of the sentence.

So 工場を見学したときは means something like:

• As for when I toured the factory...
• When I toured the factory...

It adds a slight sense of setting the scene or highlighting that occasion. In many cases, the sentence would still work without は, but は makes the time frame more clearly the topic.

Here, 場所 is the direct object of 確認しました.

• 場所 = location/place
• を = marks the thing being checked/confirmed
• 確認しました = checked/confirmed

So 場所を確認しました means checked the location.

The sentence has two different verbs, so each can have its own object:

• 工場を見学した
• 場所を確認しました

This part means the locations of the emergency exits and helmets.

Breakdown:

• 非常口 = emergency exit
• と = and
• ヘルメット = helmet
• の場所 = location/place of

So the structure is basically:

• [A と B] の場所 = the location(s) of A and B

In natural English, we would usually say the locations of the emergency exits and helmets rather than the place of emergency exits and helmets.

Not necessarily. Japanese often uses 場所 in a general sense, and the meaning can still be plural in English.

So even though 場所 is singular in form, the sentence can naturally mean:

• where the emergency exits are
• where the helmets are

If needed, Japanese could be more explicit, but this version is normal and understandable.

確認しました means checked or confirmed. It suggests making sure of something carefully.

That is a good fit here because in a factory visit, checking safety information is deliberate.

Compare:

• 見ました = looked at / saw
  
  • just visually saw them
• 分かりました = understood / came to know
  
  • focuses on understanding
• 確認しました = checked/confirmed
  
  • focuses on making sure

So 確認しました is the most appropriate for safety procedures.

Yes, the subject is omitted, which is very common in Japanese.

From 見学した and 確認しました, we understand that the same person probably did both actions, so the sentence implies something like:

• I toured the factory and checked...
• or we toured the factory and checked...

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

Yes. とき is flexible, and the best English translation depends on context.

In this sentence, possible translations include:

• when I toured the factory
• during the factory tour
• on the occasion of visiting the factory

Because the two actions are closely connected, English may prefer during the factory tour, even though Japanese literally uses when.

Yes, it often can.

• 工場を見学したとき、非常口とヘルメットの場所を確認しました。
• 工場を見学したときは、非常口とヘルメットの場所を確認しました。

Both are natural.

The version with は gives slightly more emphasis to that time frame, as if saying:

• As for when I toured the factory, I checked...

Without は, it is a little more neutral and straightforward.

Most likely, yes.

The past forms:

• 見学した
• 確認しました

make it sound like a completed event in the past. So the sentence most naturally describes something that happened on a specific occasion, such as a factory visit or tour.

The comma helps separate the time-setting part from the main statement:

• 工場を見学したときは、 = time/topic frame
• 非常口とヘルメットの場所を確認しました。 = main action

Japanese commas are often used for readability, and this is a very natural place to put one. The sentence could sometimes appear without it, but the comma makes it easier to read.