takusan no simin ga ibento ni sankasimasita.

In this sentence, たくさんの市民 means many citizens.

Here, たくさん is being used like a quantity expression before a noun, and の links it to the noun:

• たくさんの市民 = many citizens
• たくさんの人 = many people
• たくさんの本 = many books

Without の, たくさん often works more like an adverb:

• 市民がたくさん参加しました = Citizens participated in large numbers / A lot of citizens participated.

So:

• たくさんの + noun = many + noun
• たくさん + verb = a lot / in large numbers

が marks 市民 as the grammatical subject of the sentence:

• 市民が参加しました = Citizens participated.

In this sentence, が simply identifies who did the action.

If you used は, the nuance would change:

• 市民はイベントに参加しました can sound more like as for the citizens, they participated in the event, possibly contrasting them with someone else.

So here, が is the most neutral way to say that many citizens participated.

The verb 参加する usually takes に for the thing you participate in.

So:

• イベントに参加する = to participate in an event
• 会議に参加する = to participate in a meeting
• 試合に参加する = to participate in a match

English uses in or sometimes participate in, but Japanese uses に with 参加する.

So イベントに参加しました means participated in the event.

参加しました comes from the noun/verb combination 参加する, which means to participate.

Breakdown:

• 参加 = participation
• する = to do
• しました = polite past form of します

So:

• 参加する = participate / to participate
• 参加します = participate / will participate (polite)
• 参加しました = participated (polite past)

This is a very common pattern in Japanese:

• 勉強する = to study
• 運動する = to exercise
• 参加する = to participate

Japanese sentences typically place the main verb at the end.

This sentence is structured like:

• たくさんの市民が = many citizens
• イベントに = in the event
• 参加しました = participated

So Japanese often follows a subject/object/details + verb pattern.

That is one reason English speakers often feel Japanese word order is reversed compared with English.

Not exactly in the same way as English many.

たくさん is a quantity word meaning a lot / many / much, but it behaves a little differently from normal Japanese adjectives.

Common uses:

• たくさんの人 = many people
• 人がたくさんいる = there are many people
• たくさん食べる = eat a lot

So it can modify nouns with の, and it can also act adverbially.

The readings are:

• 市民 = しみん = citizen(s)
• 参加 = さんか = participation / joining

Full sentence reading:

• たくさんのしみんがイベントにさんかしました。

Also:

• イベント is katakana and is read いべんと

イベント is a loanword borrowed from English event, so it is written in katakana, the script commonly used for:

• foreign loanwords
• some onomatopoeia
• emphasis
• certain names and technical terms

So:

• イベント = event
• パーティー = party
• スポーツ = sports

Many modern words of foreign origin are written this way.

Yes. Both are natural translations.

たくさんの市民 can be translated as:

• many citizens
• a lot of citizens

In natural English, many citizens may sound a bit more formal, while a lot of citizens is more conversational.

Japanese たくさん itself does not strongly force one or the other; the best translation depends on tone.

Yes, and it often sounds a bit more formal or written.

Compare:

• たくさんの市民がイベントに参加しました。 = many citizens participated in the event
• 多くの市民がイベントに参加しました。 = many citizens participated in the event

Both are correct, but:

• たくさんの feels very common and everyday
• 多くの often feels more formal, objective, or report-like

So in news, announcements, or formal writing, 多くの市民 is very common.

It can be either in grammar, but in meaning here it is clearly plural.

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

• 市民 can mean citizen or citizens

The quantity expression たくさんの tells us it must mean many citizens, so plural is understood from context.

This is very common in Japanese:

• 学生が来ました = a student came / students came
• 三人の学生が来ました = three students came

No. Normal Japanese writing does not usually use spaces between words.

This sentence would normally be written as:

• たくさんの市民がイベントに参加しました。

Learner materials often add spaces to make the structure easier to see, but standard Japanese does not.

Yes. That is also natural Japanese.

Because particles show each word’s role, Japanese word order is more flexible than English.

These are both correct:

• たくさんの市民がイベントに参加しました。
• イベントにたくさんの市民が参加しました。

The basic meaning stays the same. The difference is mostly in emphasis or flow. Putting イベントに earlier can slightly foreground the event.

Because 参加する normally uses に, not で.

で often marks the place where an action happens:

• 公園で遊ぶ = play at the park
• 学校で勉強する = study at school

But 参加する is not just about location; it is about joining something. So Japanese treats the event as the thing being joined:

• イベントに参加する = participate in the event
• 会議に参加する = participate in the meeting

So に is the standard particle here.

Yes. 参加しました is the polite past form.

Compare:

• 参加した = participated (plain form)
• 参加しました = participated (polite)

The sentence as written is appropriate for normal polite conversation, writing, announcements, and textbook examples.

If you were speaking casually, you might say:

• たくさんの市民がイベントに参加した。

But the polite form is usually the safer default for learners.