Learn Hardcore German: Wir müssen jetzt weitergehen, sonst verpassen wir den Zug. - We have to keep going now, otherwise we will miss the train.

Müssen expresses necessity or obligation, often because of an external circumstance or a strong internal need. In this sentence, the external circumstance is the train schedule: if you do not continue now, you will miss the train.

Wir müssen jetzt weitergehen = We have to / must keep going now (otherwise we miss it).
Wir sollen jetzt weitergehen would mean: We are supposed to keep going now (because someone told us or because that’s the plan). It’s weaker and more about a recommendation or order than an unavoidable necessity.

Given the context (catching a train on time), müssen is the natural choice.

Why is müssen in second position and weitergehen at the end?

In a normal main clause, German word order is:

Position 1 – Verb 1 (conjugated) – … – other elements – Verb 2 (infinitive/participle) at the end

Here:

Wir → Position 1 (subject)
müssen → finite (conjugated) verb in position 2
jetzt → time adverb
weitergehen → infinitive verb at the end

So: Wir | müssen | jetzt | weitergehen.

Modal verbs like müssen, können, wollen behave like this: the modal itself is in second position, and the main verb (gehen) appears as an infinitive at the end (weitergehen). This is a core pattern in German.

Why is weitergehen written as one word instead of weiter gehen?

Weitergehen is a separable-prefix verb:

Base infinitive: weitergehen (one word)
In simple present without a modal: Wir gehen weiter. (prefix separates)
With a modal verb: Wir müssen weitergehen. (infinitive stays together at the end)

So:

Conjugated, no modal: gehen is conjugated, weiter separates and usually goes to the end:
Wir gehen weiter.
With modal: the main verb returns to its infinitive form and is written as weitergehen:
Wir müssen weitergehen.

Writing wir müssen weiter gehen (two words at the end) is generally considered incorrect in standard spelling.

What exactly does weitergehen mean here?

Literally, weitergehen means to go on / to continue going.

Context decides whether that is “continue walking”, “move on”, or “keep going” in English. In this sentence, you are likely walking toward the train station, so weitergehen means something like:

We need to keep walking now
We have to continue on now

The idea is: don’t stop, keep moving in the same direction or with the same activity.

Why is jetzt placed between müssen and weitergehen? Could it go somewhere else?

The most neutral word order is:

Wir müssen jetzt weitergehen. (time adverb between modal and infinitive)

Other possible positions:

Jetzt müssen wir weitergehen. (emphasis on “now”)
Wir müssen weitergehen, jetzt. (spoken: “now” as an extra push; feels more like an afterthought)

Generally:

Time adverbs like jetzt, heute, morgen often come early in the middle field of the sentence, after the finite verb but before the main/infinitive verb.
Putting jetzt at the beginning (Jetzt müssen wir…) gives it extra emphasis: Now (as opposed to before or later) is when we must go.

What does sonst mean here, and how is it used grammatically?

In this sentence, sonst means otherwise / or else and introduces a consequence if the first part is not fulfilled:

Wir müssen jetzt weitergehen, sonst verpassen wir den Zug.
→ We have to keep going now, otherwise we miss the train.

Grammatically:

sonst is an adverb, not a subordinating conjunction.
That’s why the word order after sonst is a normal main clause with verb-second (V2):
sonst | verpassen | wir | den Zug

You cannot say sonst wir verpassen den Zug in standard German; the verb must still be in second position.

Why is it verpassen wir den Zug and not something like wir den Zug verpassen after sonst?

Because sonst does not create a subordinate clause; it just links two main clauses.

Main clause word order in German: finite verb in second position.
After sonst, you still have a main clause:
- sonst → position 1 (adverb)
- verpassen → position 2 (finite verb)
- wir den Zug → rest of the clause

So the structure is:

[Wir müssen jetzt weitergehen], [sonst verpassen wir den Zug].

Each bracketed part is a main clause with verb-second word order.

Why is it den Zug and not der Zug?

Zug (train) is a masculine noun:

Nominative singular: der Zug
Accusative singular: den Zug

In this sentence, Zug is the direct object of the verb verpassen (to miss something):

Wer verpasst was?
wir (subject, nominative) verpassen den Zug (object, accusative).

Because it is a masculine noun in the accusative case, you must use den instead of der:

der Zug → subject (nominative)
den Zug → direct object (accusative)

Why is Zug capitalized?

In German, all nouns are capitalized, regardless of where they appear in the sentence.

Zug is a common noun (a thing), so it must start with a capital letter.
This rule applies even if the noun is in the middle of the sentence: den Zug, das Haus, meine Mutter.

Why is the present tense (verpassen) used for a future meaning (“will miss the train”)?

German often uses the present tense to talk about the future when the time reference is clear from context or from time expressions.

Wir müssen jetzt weitergehen, sonst verpassen wir den Zug.
Literally: “otherwise we miss the train,” but in natural English: “otherwise we will miss the train.”

You could also say:

… sonst werden wir den Zug verpassen.

This uses the future tense (werden + infinitive) and is grammatically correct, but in everyday speech the simple present (verpassen) is more common and sounds more natural when talking about near-future events that are clearly implied, like timetables or plans.