Jeg ved ikke, om min søster kommer med tog eller med bus.

In this sentence, om means whether / if and introduces an indirect yes-no question:

Jeg ved ikke, om min søster kommer med tog eller med bus.

So it is like saying: I don’t know whether my sister is coming by train or by bus.

This om is not the same as about. Danish om can have several meanings, but here it specifically introduces uncertainty between possibilities.

A common learner mistake is to confuse om with hvis.

• om = whether / if in an indirect question
• hvis = if in a condition

Compare:

• Jeg ved ikke, om hun kommer. = I don’t know if/whether she is coming.
• Hvis hun kommer, bliver jeg glad. = If she comes, I’ll be happy.

Because after om, you have a subordinate clause, and Danish subordinate clauses usually use normal subject-verb order:

• min søster kommer

In main clauses, Danish often has verb-second word order:

• Min søster kommer med tog.
• I dag kommer min søster med tog.

But in a subordinate clause introduced by om, the structure is more straightforward:

• ..., om min søster kommer med tog ...

So the pattern is:

• main clause: Jeg ved ikke
• subordinate clause: om min søster kommer med tog eller med bus

In a main clause, Danish usually places the finite verb before ikke.

So:

• Jeg ved ikke = I do not know

This is the normal Danish word order for negation in a main clause:

• subject + finite verb + ikke

Examples:

• Jeg kommer ikke.
• Hun spiser ikke kød.

If the negation were inside a subordinate clause, it would usually come before the main verb phrase:

• ..., om min søster ikke kommer med tog.

So in your sentence, ikke belongs to the main clause Jeg ved ikke.

Because in Danish, means of transport are often expressed without an article after med:

• med tog = by train
• med bus = by bus
• med bil = by car
• med fly = by plane

This works similarly to English by train rather than by a train.

If you add an article, the meaning changes and usually becomes more specific:

• med toget = on the train / by the train (a specific train)
• med bussen = on the bus / by the bus (a specific bus)

So in your sentence, no article is used because it refers to the general mode of transport.

Yes, you may hear or see med repeated, as in:

med tog eller med bus

This is very clear and fully natural.

You can also sometimes omit the second med:

• med tog eller bus

But repeating med is common because it makes the parallel structure clearer, especially for learners and in careful speech.

So both can work, but:

• med tog eller med bus = slightly more explicit
• med tog eller bus = a bit more compact

Yes, grammatically it is the present tense of komme = to come.

But in context, kommer med tog / med bus often sounds more natural in English as:

• is coming by train
• is arriving by train
• sometimes even will come by train, depending on context

Danish present tense often covers situations where English might use:

• present progressive: is coming
• simple future: will come

So kommer here is present tense in form, but its best English translation depends on context.

Both forms exist in Danish, but min søster is the neutral and most common way to say my sister.

• min søster = standard, neutral
• søsteren min = also possible, often more emphatic, contrastive, or slightly more spoken in some contexts

In most ordinary sentences, learners should default to:

• min bror
• min søster
• min mor
• min ven

So min søster is exactly what you would expect here.

The comma marks the start of the subordinate clause:

• Jeg ved ikke, om min søster kommer med tog eller med bus.

In Danish, commas are used to separate clauses. Since om min søster kommer med tog eller med bus is a subordinate clause, many writers place a comma before it.

You should also know that modern Danish comma rules allow some variation depending on whether someone uses start comma or not. So you may also see:

• Jeg ved ikke om min søster kommer med tog eller med bus.

Both may occur, depending on the writer’s comma style. If you are learning, it is useful to recognize both.

Eller means or and links the two alternatives:

• med tog
• med bus

So the sentence presents two possibilities and says the speaker does not know which one is true.

You could think of the structure as:

• whether X or Y

Danish does not need either here, though you could add enten in some cases for emphasis:

• ..., om min søster kommer enten med tog eller med bus.

But in ordinary Danish, eller alone is perfectly natural.

Yes, in English it is often translated as if:

• I don’t know if my sister is coming by train or by bus.

That is natural English.

However, for grammar learning, it is useful to remember that Danish om here really corresponds to whether in the sense of uncertainty between possibilities. That is why whether is often the clearest explanation, even though English speakers often say if in everyday speech.

So:

• natural English translation: if
• grammar explanation: whether

It can easily be about the future, even though Danish uses the present tense kommer.

Danish very often uses the present tense for future events when the context makes the time clear.

So min søster kommer med tog eller med bus can mean:

• my sister is coming by train or by bus
• my sister will come by train or by bus

This is normal Danish usage. English also sometimes does something similar, especially with arrangements:

• She’s coming tomorrow.

Yes, but the wording would be different.

Your sentence uses:

• kommer med tog / med bus

This focuses on how she is coming.

You could also say:

• Jeg ved ikke, om min søster tager toget eller bussen.

That means:

• I don’t know whether my sister is taking the train or the bus.

This version is also very natural, but it refers more directly to the chosen vehicle. Notice that with tage, you would normally use the definite form:

• toget
• bussen

So the two patterns are:

• komme med tog / bus
• tage toget / bussen

Both are common, but they are built differently.

That is a very common question. In standard spoken Danish, jeg is usually pronounced something like yai or yigh, depending on the speaker and region. It is often much softer than English speakers expect.

A few rough pronunciation notes:

• jeg: often sounds like yai
• ikke: often sounds closer to eg-ge or ig-ge than the spelling suggests
• søster: the ø sound is important and does not exist exactly in English
• tog: the final g is usually soft or silent in practice
• bus: fairly close to English boos with a short vowel
• om: short and unstressed here

The important thing for learners is that spoken Danish is often less phonetic than the spelling suggests. So this sentence may sound much more reduced in real speech than it looks on the page.