eki de siriai ni aimasita.

で marks the place where an action happens. So 駅で means at the station or in the station, depending on the situation.

In this sentence, the action is meeting someone, and that meeting happened at the station.

• 駅で会いました = met (someone) at the station

This is different from に, which often marks a destination, time, or the target of certain verbs.

The verb 会う usually takes に for the person you meet.

So:

• 知り合いに会いました = met an acquaintance

Even though English says meet someone, Japanese does not usually use を here. With 会う, the person is normally marked by に.

Examples:

• 先生に会いました。 = I met my teacher.
• 友達に会いました。 = I met my friend.

Because 会う does not normally use を for the person being met.

A learner might expect を because in English someone looks like a direct object, but Japanese grammar works differently here. 会う takes に.

So this is correct:

• 知り合いに会いました。

And this is not natural:

• 知り合いを会いました。

Not exactly. 知り合い means acquaintance, someone I know, or a person I’m acquainted with. It is usually less close than 友達.

So:

• 友達 = friend
• 知り合い = acquaintance / someone I know

If you say 知り合いに会いました, it sounds like you met someone you know, but not necessarily a close friend.

会いました is the polite past form of 会う.

Breakdown:

• dictionary form: 会う
• polite non-past: 会います
• polite past: 会いました

So the sentence is polite and means that the meeting happened in the past.

If you wanted a casual version, you could say:

• 駅で知り合いに会った。

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

So 駅で知り合いに会いました。 often naturally means:

• I met an acquaintance at the station.

But depending on context, it could also mean:

• He met an acquaintance at the station.
• She met an acquaintance at the station.
• They met an acquaintance at the station.

Japanese does this very often, especially when the subject is obvious from the situation.

Yes, Japanese nouns usually do not change form for singular vs. plural.

So 知り合い can mean:

• an acquaintance
• acquaintances

In this sentence, it will usually be understood from context. Without extra information, many learners read it as singular, but plural is also possible in the right situation.

If you wanted to make plurality clearer, you might say:

• 知り合いたちに会いました = I met my acquaintances

But Japanese often just leaves it ambiguous.

Here, で is used because the station is the location where the action happened.

• 駅で会いました。 = met (someone) at the station

If you used 駅に, it would not sound natural for the location of the meeting itself in this sentence.

Compare:

• 駅に行きました。 = went to the station
  (に marks destination)
• 駅で会いました。 = met at the station
  (で marks location of action)

So で is the right particle here.

Yes, very natural.

Japanese often omits 私は, 彼は, and other topics when they are already understood. Adding 私は is possible, but it is not necessary.

For example:

• 私は駅で知り合いに会いました。 = I met an acquaintance at the station.

This is grammatically fine, but in normal conversation Japanese often drops 私は unless there is a reason to emphasize or contrast it.

No. Standard Japanese is usually written without spaces.

So normally this would be written as:

• 駅で知り合いに会いました。

Spaces are often added only in beginner materials to make the sentence easier to read.

In this sentence, 会いました means met.

The verb 会う usually means to meet someone, either intentionally or by chance, depending on context. It is used for encountering people.

So:

• 知り合いに会いました = met an acquaintance

If you want to say simply saw in the visual sense, Japanese often uses 見る instead.

Yes. Depending on context, 知り合いに会いました can sound like:

• I met an acquaintance
• I ran into someone I know
• I saw an acquaintance at the station

The exact nuance depends on the situation. Japanese does not always force the same distinction English does between met intentionally and ran into by chance unless more detail is added.