Minun on pakko miettiä hetki ennen kuin vastaan.

I have to think for a moment before I answer.

Breakdown of Minun on pakko miettiä hetki ennen kuin vastaan.

• minä: I
• olla: to be
• hetki: the moment
• ennen kuin: before
• vastata: to answer
• pakko: necessity
• miettiä: to think

Questions & Answers about Minun on pakko miettiä hetki ennen kuin vastaan.

Why is minun in the genitive case here, instead of minä?

In the expression minun on pakko, pakko (“compulsion, must”) is the grammatical subject of on (3rd sg of olla), and minun marks the possessor of that “compulsion.” Literally it means “it is a compulsion of me to think…,” i.e. “I have to think…”

What does pakko mean, and how does it compare with täytyy?

• pakko is a noun (“compulsion, must”) used in the impersonal construction on pakko + INF.
• täytyy is an impersonal modal verb (“must”) that also takes an infinitive: täytyy miettiä.
  Nuance: pakko can feel a bit stronger or externally imposed, while täytyy is more neutral. In everyday speech they’re often interchangeable:
  • Minun on pakko miettiä…
  • Minun täytyy miettiä…

Why is hetki not in the partitive case (i.e. hetken) for a duration?

Standard Finnish uses the partitive for durations: miettiä hetken. So the fully correct form is
Minun on pakko miettiä hetken ennen kuin vastaan.
Colloquially some drop the partitive and say miettiä hetki, but if you want to follow the grammar rule for durations, use hetken.

What role does ennen kuin play, and could you use ennen with a nominal form instead?

• ennen kuin is a subordinating conjunction meaning “before” + a finite clause: ennen kuin vastaan (“before I answer”).
• Alternatively, you can use ennen
  • the -minen noun in partitive: ennen vastaamista (“before answering”).
    Example:
    Minun on pakko miettiä hetken ennen vastaamista.

Why is there no separate pronoun with vastaan, and why does it end with -n?

vastaan is the 1st person singular present tense of the verb vastata (“to answer”). The ending -n marks “I,” so you don’t need a separate pronoun (minä) unless you want to emphasize the subject.

Can you omit minun and just say On pakko miettiä hetken ennen kuin vastaan?

Yes. Especially in spoken and informal Finnish, dropping minun is common if context makes the person clear:
On pakko miettiä hetken ennen kuin vastaan.
Adding minun is more neutral or formal and clarifies that you (i.e. “me”) are the one obliged.

How would you express the same idea about someone else, for example “You have to think for a moment before you answer”?

Change the genitive pronoun and the verb form in the subordinate clause:
Sinun on pakko miettiä hetken ennen kuin vastaat.
Here sinun is 2nd person genitive, and vastaat is 2nd person singular present.

Could you rephrase the sentence more colloquially or simply in Finnish?

Sure, here are a few alternatives:
• Mun täytyy miettiä hetken ennen kuin vastaan. (colloquial mun, uses täytyy)
• Pakko miettiä hetki ennen kuin vastaan. (drops pronoun and copula)
• Mä mietin hetken ennen kuin vastaan. (simple future nuance: “I’ll think for a moment before answering.”)