Learn Hardcore Korean: jibe gagi jeone kkok soneul ssiseoya haeyo. - Be sure to wash your hands before going home.

The ending -기 전에 attaches to a verb stem to mean “before doing …”. Here, 가- (to go) + -기 creates a noun form 가기 (“going”), and 전에 (“before”) follows it. So 집에 가기 전에 literally means “before the going to home.”

Why is 가기 used instead of 가는 or 가다 in 집에 가기 전에?

You need the -기 nominalizer to turn 가다 (the dictionary form) into a noun (“going”), because 전에 expects a noun. 가는 is the attributive form (“going …” as an adjective), which doesn’t combine with 전에 to mean “before doing.” Only -기 전에 expresses “before [verb]-ing.”

What nuance does 꼭 add to 꼭 손을 씻어야 해요?

꼭 means “without fail,” “certainly,” or “make sure to.” It emphasizes that washing your hands is mandatory or very important. Without 꼭, the sentence still means “You must wash your hands,” but with 꼭 it’s stronger: “Be sure to wash your hands.”

How is the obligation expressed in 손을 씻어야 해요?

Obligation in Korean often uses verb stem + -아/어야 하다.
• 씻다 → stem 씻- + 어야 = 씻어야 (“must wash”)
• Then add 하다, conjugated politely as 해요.
So 씻어야 해요 = “you have to wash.”

What is the difference between 씻어야 해요 and 씻어야 돼요?

Both express necessity, but:
• 씻어야 해요 focuses on the speaker’s judgment (“I say you must wash”).
• 씻어야 돼요 comes from 되다 (“to become”), meaning “it becomes that you must wash,” sounding a bit more like an external rule or situation. In daily speech they’re interchangeable.

Why is the object particle -을 used in 손을 씻다?

손 (“hand”) is the direct object of 씻다 (“to wash”), so it takes the object marker 을 (after a consonant). Thus 손을 씻다 means “to wash one’s hands.”

What politeness level is ~해야 해요, and is it appropriate in formal situations?

~해야 해요 uses the polite -요 ending, known as 해요체 (polite style). It’s appropriate for everyday polite conversation with acquaintances, colleagues, or strangers. For very formal or official contexts you might use ~해야 합니다 instead.

Could the sentence be rearranged in a different word order in Korean? How flexible is it?

Korean is relatively flexible because case markers (like 에, -을) show each word’s role. You could say:
• 꼭 손을 씻고 집에 가기 전에 해요 (less natural)
• 집에 가기 전에 손을 꼭 씻어야 해요 (moves 꼭 after 손을 without changing meaning)
But the main verb 씻어야 해요 must stay at the end of its clause. The time clause 집에 가기 전에 normally comes before the main verb.