hai, doa o akete haitte mo ii desu.

Yes, you may open the door and come in.

Breakdown of hai, doa o akete haitte mo ii desu.

• です: to be
• を: direct object particle
• ドア: door
• 開あける: to open
• 〜て: connective form
• 入はいる: to enter
• はい: yes
• 〜て も いい: to be permitted to

Questions & Answers about hai, doa o akete haitte mo ii desu.

Why are there two verbs, 開けて and 入って, and why are they both in the て-form?

In Japanese, the て-form serves two purposes here:

1. It links multiple actions in sequence.
2. It also connects the first action to the permission structure for the second.
   So ドアを開けて入る means “open the door and enter,” and by using 開けて you smoothly connect to 入ってもいいです for granting permission.

What is the structure 動詞-てform + も + いいです, and how does it express permission?

The pattern V-て + も + いいです literally means “even if you do V, it’s good,” but idiomatically it means “you may V” or “it’s okay to V.”
• 開けて入ってもいいです＝“You may open (the door) and enter.”
• To ask for permission you add か: 開けて入ってもいいですか？ (“May I open and enter?”).

Why is there no か at the end of 開けて入ってもいいです?

Because this sentence is the speaker granting permission, not asking.
• For a question (requesting permission) you need か: …もいいですか？
• For an answer (giving permission) you use a declarative いいです without か.

What nuance does starting with はい add in this sentence?

はい here means “yes” or “sure.” It acknowledges the listener’s request and signals that you’re about to grant permission. It’s polite and confirms that you’re responding to something previously asked.

Why is the particle を used after ドア?

を marks the direct object of a transitive verb. Since ドア is what you’re opening, you attach を to show that relationship:
ドア (object) + を + 開ける (verb).

What role do the commas (、) play in はい、ドアを開けて入ってもいいです。?

Japanese commas (読点) indicate natural speech pauses or separate elements for clarity. Here they give a slight breath:

• After はい to confirm.
• (Optional) some writers insert one after ドア to slow the pace.

Can this sentence be made more casual?

Yes. In informal settings you can drop も and です:
ドアを開けて入っていい？
This equals “Mind if I open the door and come in?” or “Can I open and enter?”

Could I say ドアを開けてから入ってもいいです instead?

Yes, から stresses “after.”
• 開けてから入ってもいいです＝“You may open it first, and then (only after that) enter.”
• Without から, 開けて入ってもいいです already implies the natural order.

What’s the difference between using いいです and かまいません for granting permission?

• いいです is the most common, neutral way to say “that’s fine.”
• かまいません is a bit more formal or emphatic “it doesn’t matter.”
Meaning is almost the same, though tone and formality differ.