Learn Hardcore Korean: jigabe yeogwongwa bihaenggi pyoreul neoheosseoyo. - I put my passport and plane ticket in my wallet.

In Korean, it’s very common to omit the subject when it’s clear from context. Since you’re talking about what you did, “I” is understood. If you needed to emphasize or clarify the subject, you could say:

저는 지갑에 여권과 비행기 표를 넣었어요.
내가 지갑에 여권과 비행기 표를 넣었어.

What is the function of the particle 에 after 지갑? Why not use 안에 or 에서?

The particle 에 here marks the target location or destination of the action “put.” Even though it looks like a simple locative “at,” with verbs like 넣다 (to put into), 에 actually means “into” or “in.”

지갑에 넣었어요. → “I put (something) into the wallet.”

You could use 안에 to explicitly say “inside”:

지갑 안에 여권과 비행기 표를 넣었어요.
But Koreans often omit 안 because 넣다 + 에 already implies putting something inside.

By contrast, 에서 marks the place where an action happens (the “from” or “at” for ongoing actions), so 지갑에서 넣었어요 would sound like “I did the putting at the wallet,” which is unnatural here.

Why is only 비행기 표 marked with 를, not 여권?

When you have a list of direct objects connected by 과/와, you only need to attach the object marker 를/을 to the last item. It’s more concise and sounds natural.

Standard: 지갑에 여권과 비행기 표를 넣었어요.
You could also mark each noun (but it’s a bit redundant): …여권을, 비행기 표를 넣었어요.

Why do we use 과 to connect 여권 and 비행기 표? What’s the difference between 과, 와, 하고, and 랑?

All these mean “and” (to link nouns), but they differ by formality and sound:

과: formal/written, used after a consonant-final noun (여권 ends in ㄴ → 여권과).
와: formal/written, used after a vowel-final noun (e.g. 친구 → 친구와).
하고: neutral/informal, works after consonants or vowels (여권하고).
랑: casual/spoken, works after consonants or vowels (여권이랑).

So 여권과 비행기 표 is slightly more formal or textbook style than 여권하고 비행기 표.

How do you form the past polite tense 넣었어요 from the verb 넣다?

Remove the dictionary ending -다 from 넣다 to get the stem 넣-.
Add the past tense marker -었-.
Finish with the polite ending -어요.

So:
넣 + 었 + 어요 → 넣었어요 (“put” in polite past).

Why is 비행기 표 written as two separate words instead of one?

In Korean, many noun-noun combinations are written with a space when the first noun describes the second. Here:

비행기 (airplane) + 표 (ticket) → “plane ticket.”
Similarly you see 버스 표, 영화 표, 기차 표.
By contrast, fully bound compounds (often from two Hanja roots) like 여권 (passport) are written without a space.

Can I change the word order of this sentence?

Yes. Korean is flexible because particles mark each word’s role. As long as the verb stays at the end, you can swap location and objects for emphasis or style:

여권과 비행기 표를 지갑에 넣었어요.
지갑에 비행기 표와 여권을 넣었어요.

All these mean essentially the same thing; you’re just shifting focus.