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

Questions & Answers about hai, doa wo akete haitte mo ii desu.
In Japanese, the て-form serves two purposes here:
- It links multiple actions in sequence.
- 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.
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?”).
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.
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).
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.
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?”
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.
• 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.