Learn Hardcore Japanese: seki ha mou yoyakusite aru kara, narabu hituyou ha nai. - The seats are already reserved, so we don’t need to line up.

〜てある with a transitive verb describes a state that exists now as the result of someone’s intentional, completed action. So 予約してある means “(someone) has made a reservation, and that reservation is in place now,” with an implicit nuance of preparation.

State/result focus: 窓が開けてある = “The window has been opened (by someone) and is (left) open.”
It’s different from simply saying an action happened; it highlights the current, purposeful result.

Why is it ある and not いる in してある?

〜てある is a fixed pattern that always uses ある (not いる) because it states an inanimate “resulting state” produced by an intentional action. It’s not about an animate subject existing; it’s about a state that exists.

Could I say 予約している instead of 予約してある? What’s the nuance difference?

Both are possible but differ in nuance:

予約してある: Emphasizes a prior, intentional action done in preparation, and its result now (strong “we already took care of it” feel).
予約している: States an ongoing state “we have a reservation.” It’s neutral and common in self-introductions at a restaurant (e.g., 予約している者です).

How about 予約がある? Does that work?

Yes. 予約がある simply means “there is a reservation / we have a reservation,” without the “done in preparation” nuance. It’s neutral and factual.

Why is it 席は and not 席が or 席を?

席は: Topic-marking. “As for the seat(s), they’re already reserved…” It frames what follows.
席が: Subject-marking. 席がもう予約してある focuses on the existence of reserved seats. Also natural.
席を: Also possible in this pattern (e.g., 席を予約してある), and it focuses more on the action you (or someone) performed in preparation (“I/we have reserved seats”). With 〜てある, you’ll often see either が/は (state focus) or を (prep action focus), depending on what you want to highlight.

Is it okay that there are two instances of は in the sentence (席は … 必要はない)?

Yes. Japanese can have multiple は. Each は sets up a different topic/contrast:

席は: “As for seats…”
必要はない: The は here adds a contrastive nuance: “(at least) there’s no need.”

Why is it 必要はない instead of 必要がない or just 必要ない?

All are acceptable, with nuances:

必要はない: Contrastive/emphatic “there’s no need (at all / in this case).”
必要がない: Plain statement “there is no need.”
必要ない: Colloquial, particle omitted; widely used in speech.

What does 並ぶ必要はない literally mean? Why is 並ぶ in dictionary form?

It’s “There is no need to line up.” In Japanese, the dictionary form of a verb can directly modify a noun: 並ぶ必要 = “the need to line up.” So the structure is [Verb-plain] + 必要 (+ は/が) + ない.

Can I say 並ばなくていい instead of 並ぶ必要はない?

Yes, but the nuance differs:

並ぶ必要はない: Speaks about necessity; “no need to line up.”
並ばなくていい / 並ばなくてもいい: Permission/comfort; “you don’t have to line up / it’s okay not to line up.” In casual speech, this is very common.

What’s the difference between から, ので, and だから here?

Clause + から: Reason/cause; neutral and common. Example: 席はもう予約してあるから、並ぶ必要はない。
Clause + ので: Softer/more formal; often preferred in polite contexts. Example: 席はもう予約してありますので、並ぶ必要はありません。
だから: “Therefore/so” between two sentences. Example: 席はもう予約してある。だから、並ぶ必要はない。 (Don’t say “予約してあるだから …” in one clause.)

Could I use 予約しておいた? How does that compare to 予約してある?

予約しておいた: “I (went ahead and) reserved (in advance)”—focus on the prior preparatory action from the doer’s perspective.
予約してある: Focus on the resulting state now (“the reservation is in place”). Both can fit, but the original sentence wants the present-result nuance.

What’s the role of もう here? Can it mean “anymore”?

Here もう means “already”: 席はもう予約してある = “the seat(s) are already reserved.”
With negation, もう often means “no longer/anymore,” e.g., もう並ぶ必要はない = “There’s no need to line up anymore.” In the given sentence, もう modifies the reservation clause, not the negation.

Can I move もう or change the word order?

Yes, small shifts are fine:

もう席は予約してあるから… (slightly stronger “already” focus)
席はもう予約してあるから… (neutral) Both are natural. Japanese word order is flexible, but keep the reason before から (or make two sentences).

Is it okay to finish a sentence with から?

Yes, conversationally. You can say: 並ぶ必要はない。席はもう予約してあるから。 The second sentence ends with から and functions as “because…,” with the main clause understood from context.

Could I topicalize the reservation instead, like 予約はもうしてある?

Yes. 予約はもうしてあるから、並ぶ必要はない。 This puts focus on the reservation itself (“As for the reservation, it’s already done…”). It’s a natural alternative.

What’s a polite version of the whole sentence?

席はもう予約してありますから、並ぶ必要はありません。
This uses ます/ません and is appropriate in formal situations.

Is 席 singular or plural here?

Japanese doesn’t mark number by default. 席 can mean “a seat” or “seats,” depending on context. If you need to be explicit, add a counter, e.g., 席を二つ予約してあります (“We’ve reserved two seats”).

How do I say this naturally to a host at a restaurant?

When you arrive, you’d usually say something like:

予約しています、[Name] です。 (“We have a reservation; [Name].”)
If clarifying reason: 席は予約してありますので、並ばなくても大丈夫です。

Why are there spaces between the words in the given sentence?

They’re for learners. Standard Japanese writing does not put spaces between words: 席はもう予約してあるから、並ぶ必要はない。