Learn Hardcore Dutch: Neem dit serieus, want de dokter belt straks. - Take this seriously, because the doctor will call shortly.

Informal singular: Neem dit serieus.
Polite with u: Neemt u dit alstublieft serieus.
Addressing a group: still the stem: Neem dit serieus, allemaal. There’s no form Nemen! for the imperative, and Neemt! is only used with polite u: Neemt u…

Can I say Het instead of Dit? What’s the difference between Neem dit serieus and Neem het serieus?

Both are possible, but:

dit points to something specific and present in the context: “this (thing/situation).”
het is more neutral/generic: “it.” If you’re holding a form or referring to the current issue, Neem dit serieus is slightly more pointed. If the referent is already clear, Neem het serieus is fine. For far/previously mentioned items, you can also get dat (“that”).

Why is there a comma before want? Is it required?

want is a coordinating conjunction (“because/for”). A comma before it is common and stylistically recommended, especially in writing: Neem dit serieus, want… In short sentences you’ll also see it without a comma: Neem dit serieus want… Both are acceptable.

Why doesn’t the verb go to the end after want?

Because want is a coordinator, not a subordinator. It keeps main-clause order:

… want de dokter belt straks. (S–V–other) With a subordinator like omdat, the verb goes to the end:
… omdat de dokter straks belt.

What’s the difference between want and omdat?

want links two main clauses and presents an explanation/justification. Word order stays S–V. You don’t normally front a want-clause.
omdat introduces a subordinate clause expressing cause. The finite verb goes to the end, and the clause can be fronted: Omdat de dokter straks belt, moet je dit serieus nemen. Both are neutral in register; want often feels a bit more conversational as a clause linker.

Why is it spelled belt and not beldt?

3rd person singular present is “stem + t.”

bellen → bel + t = belt. You only get “dt” if the stem ends in -d:
vinden → vind + t = vindt
houden → houd + t = houdt Since the stem of bellen is bel (no d), it’s belt, not “beldt.”

Does bellen mean “to call on the phone” or “to ring the doorbell”?

On its own, bellen typically means “to call (by phone).” For doorbells, Dutch prefers aanbellen: De dokter belt straks aan = “will ring the doorbell.”
There’s also opbellen (“to call up”): Hij belt je straks op. Without an object, belt straks op sounds odd; just belt straks is the natural way to say “will call.”

What exactly does straks mean? Is it “soon” or “later”?

straks means “a bit later (today), soonish.” It’s near future, but not necessarily immediate.

Very soon: (zo) meteen / zometeen
Later today/soonish: straks
Soon (more generally): binnenkort Regional note: in Flanders, straks tends to mean “later (not right away),” while dadelijk or zometeen can mean “immediately.”

Where can straks go in the sentence?

Common placements:

End position: De dokter belt straks.
Fronted (gives emphasis, triggers inversion): Straks belt de dokter. You wouldn’t say De dokter straks belt in a main clause; that order appears only in subordinate clauses: … omdat de dokter straks belt.

Could I say De dokter gaat straks bellen or De dokter zal straks bellen?

Yes.

gaat … bellen = “is going to call,” plan/intention, very natural.
zal … bellen = “will call,” a bit more formal or predictive.
belt straks (simple present + time adverb) is the most common, everyday way to express near future.

Why is it de dokter and not het dokter, and can I drop the article?

dokter is a common-gender noun, so it takes de: de dokter (“the doctor”).
You can drop the article only if you’re using it as a title with a name or in direct address:

Dokter Jansen belt straks.
Dokter, kunt u even komen? Otherwise, use the article: De dokter belt straks.

What is serieus doing here, and why is the order Neem dit serieus (not Neem serieus dit)?

The pattern is “to take something seriously” = iets serieus nemen.
Here, serieus is a predicative complement linked to the object (dit): you “take this [in a serious way].” The normal order is object + complement: Ik vind dit belangrijk, Ze maakt me boos, Neem dit serieus.
Neem serieus dit is unidiomatic.

Can I use ernstig instead of serieus?

Sometimes.

The idiom iets serieus nemen is standard everywhere.
iets ernstig nemen is common in Belgium; in the Netherlands it can sound a bit stiff or formal.
Meaning-wise they overlap here, but serieus nemen is the safest, most idiomatic choice across varieties.

How do I pronounce the sentence?

Approximate guide (NL accent):

Neem: “naym”
dit: “dit” (short i as in “bit”)
serieus: “se-ri-YEUS” (eu like French “bleu”)
want: “vant” (Dutch w is between English v and w)
de: “duh”
dokter: “DOK-tur” (final -er is a schwa)
belt: “belt” (e as in “bed”)
straks: “strahks” (a like British “cup,” but back)
Full: “NAYM dit se-ri-YEUS, vant duh DOK-tur BELT strahks.”

How can I soften the imperative?

Add politeness: Neem dit alstublieft serieus. / Neem dit alsjeblieft serieus.
Use even to sound more friendly/brief: Neem dit even serieus.
Use a request: Wil je dit serieus nemen? / Zou u dit serieus willen nemen?

Is it okay to start a sentence with want?

In speech and informal writing, yes:

Neem dit serieus. Want de dokter belt straks. In formal writing, it’s usually better to keep want between the clauses or use omdat and a subordinate clause.