bihaenggireul tal ttae yeogwoneul boyeo juseyo.

When you board a plane, please show your passport.

Breakdown of bihaenggireul tal ttae yeogwoneul boyeo juseyo.

• ~을: object particle
• ~를: object particle
• 여권: passport
• 보여 주다: to show
• 비행기: plane
• 때: when
• 타다: to board

Questions & Answers about bihaenggireul tal ttae yeogwoneul boyeo juseyo.

What does -을 때 mean in 비행기를 탈 때, and how is it different from -면?

-을 때 literally means “when (something happens).” In 비행기를 탈 때, it marks the time of the action: “when boarding the plane.”
By contrast, -면 often carries a conditional or hypothetical sense – “if/when” rather than simply “when” at the moment something occurs.

Why is the verb 타다 changed to 탈 때 instead of using 타는 때?

When attaching -때 to a verb stem, you use the future/adnominal form (으)ㄹ + 때.
• 타다 → drop 다, add ㄹ → 탈
• Then 탈 + 때 → 탈 때 (“at the time of boarding”).
Using 타는 때 would be ungrammatical in this construction.

Why is 여권을 marked with -을 in 여권을 보여 주세요? Can you drop it?

-을 is the object particle marking 여권 as what’s being shown. It clarifies the direct object of 보여 주세요.
In casual speech you might hear 여권 보여 주세요 (dropping the particle), but including -을 is more standard and clear.

What exactly does 보여 주세요 mean, and why not just 보여요?

보여 주세요 is the polite request form of 보여 주다 (“to give the favor of showing”). It literally means “please show (it to me).”
By contrast, 보여요 is a polite declarative or intransitive “it shows” or could mean “I show,” but it’s not used as a request.

Could this sentence be more formal? For example, using -십시오?

Yes. A more formal version might be:
비행기를 탈 때 여권을 보여 주십시오.
Here, -주십시오 is the honorific imperative, often used in announcements or very polite instructions.

Is the word order fixed? Could I say 여권을 보여 주세요 비행기를 탈 때?

Standard Korean word order puts the time clause first (비행기를 탈 때) followed by the main request (여권을 보여 주세요).
Sliding the time phrase to the end sounds awkward and is not natural in Korean.