Learn Hardcore Dutch: Het is een week geleden dat zij ontbijtgranen heeft gekocht, dus de doos is bijna leeg. - It has been a week since she bought breakfast cereal, so the box is almost empty.

Why does the sentence start with Het is een week geleden dat…? Why not just say something like Een week geleden heeft zij ontbijtgranen gekocht?

Dutch has a very common pattern:

Het is X geleden dat + [clause]

Literally: It is X ago that…
Functionally, it matches English It’s been X since…

So:

Het is een week geleden dat zij ontbijtgranen heeft gekocht
≈ It’s been a week since she bought cereal.

Your alternative:

Een week geleden heeft zij ontbijtgranen gekocht
= A week ago she bought cereal.

Both are correct, but they structure the information differently:

Het is … geleden dat… focuses on the time that has passed up to now.
Een week geleden heeft zij… just states when the action took place, without that “since then until now” feeling.

In many contexts they are interchangeable, but native speakers often use Het is … geleden dat… right before giving a result or consequence (here: dus de doos is bijna leeg).

Why is it Het is and not Het was if this happened in the past?

Even though the buying happened a week ago, the point of the sentence is about now:

Het is een week geleden = It is (now) a week ago.

Dutch normally uses the present tense here, because you are talking about the current situation: right now, it has been one week since the action.

You would only use Het was een week geleden dat… if you were placing this whole “one-week gap” in the past, e.g.:

Toen we dat ontdekten, was het al een week geleden dat zij ontbijtgranen had gekocht.
When we discovered that, it had already been a week since she had bought cereal.

So in the original sentence, is is correct because it describes the present time span up to now.

Why is it dat in dat zij ontbijtgranen heeft gekocht and not wanneer or toen?

Here dat is a subordinating conjunction that simply introduces a clause, similar to English that in “that she bought cereal”.

The structure is literally:

Het is een week geleden [dat zij ontbijtgranen heeft gekocht].

You are not focusing on “when” as a question of time in the sense of a point in time; you’re just connecting the statement “it is a week ago” with the event “she bought cereal”. Dutch prefers dat here.

You would use:

wanneer (“when”) in indirect questions or some other time clauses:
- Ik weet niet wanneer zij ontbijtgranen heeft gekocht.
  I don’t know when she bought cereal.
toen (“when” in the past, “at the time that”) mainly for past-time clauses in narratives:
- Toen zij ontbijtgranen kocht, was de doos nog vol.
  When she bought cereal, the box was still full.

In the “… geleden dat …” pattern, dat is the normal and idiomatic choice.

Why does the verb go to the end in dat zij ontbijtgranen heeft gekocht?

Dutch has two main clause types regarding word order:

Main clause: the conjugated verb is in second position (V2).
- Zij heeft ontbijtgranen gekocht.
  (subject–verb–object–past participle)
Subordinate clause (after words like dat, omdat, wanneer, als…): the verbs go to the end of the clause.
- … dat zij ontbijtgranen heeft gekocht.

So the pattern in a dat-clause is:

[conjunction] + [subject] + [objects/adverbs] + [verbs at the end]

Hence:

dat (conjunction)
zij (subject)
ontbijtgranen (object)
heeft gekocht (auxiliary + past participle, both at the end)

Why is it heeft gekocht and not just kocht?

Both are grammatically possible:

dat zij ontbijtgranen heeft gekocht (perfect)
dat zij ontbijtgranen kocht (simple past)

The choice between perfect and simple past in Dutch is different from English:

In spoken Dutch, the perfect tense (heeft gekocht) is far more common for completed past events in everyday conversation.
The simple past (kocht) is used more in written narratives, stories, and sometimes in more formal or literary style.

So in natural spoken Dutch:

Het is een week geleden dat zij ontbijtgranen heeft gekocht…
sounds more usual than …dat zij ontbijtgranen kocht…

English would almost always say “since she bought cereal” (simple past), but Dutch is much freer to use the perfect there, especially in speech.

Could the word order be dat zij heeft ontbijtgranen gekocht instead of dat zij ontbijtgranen heeft gekocht?

No, dat zij heeft ontbijtgranen gekocht is not natural or standard.

General rule inside clauses:

Objects usually come before the auxiliary and participle cluster, especially in neutral sentences.

Correct patterns:

Zij heeft ontbijtgranen gekocht. (main clause)
… dat zij ontbijtgranen heeft gekocht. (subordinate clause)

Putting the object between the auxiliary and participle (heeft ontbijtgranen gekocht) is not correct in neutral word order.

What is the difference between zij and ze here? Could I say dat ze ontbijtgranen heeft gekocht?

Yes, you can say:

Het is een week geleden dat ze ontbijtgranen heeft gekocht…

zij and ze are both “she”:

zij is the strong/stressed form. It’s used:
- for emphasis: Zij heeft ontbijtgranen gekocht, niet hij.
  She bought cereal, not he did.
- at the start of a sentence in more careful or written style.
ze is the weak/unstressed form, more common in casual speech, especially in the middle of a sentence.

In your sentence, both are correct. zij might feel a bit more “careful” or slightly more emphatic; ze sounds more colloquial and neutral.

Why is ontbijtgranen plural if in English we often say just “cereal” (uncountable)?

Ontbijtgranen is literally “breakfast grains” and is normally used:

in the plural form as a kind of mass noun:
- Ik eet elke ochtend ontbijtgranen.
  I eat cereal every morning.

The singular ontbijtgraan exists but is only used for a single grain (one cornflake, one oat flake, etc.), which is rare.

So:

Dutch: zij heeft ontbijtgranen gekocht (plural form, but conceptually mass)
English: she bought (some) cereal (singular, uncountable)

This is just a difference in how each language treats the word grammatically.

Is ontbijtgranen always the right word for “cereal”? Could I say cornflakes instead?

Ontbijtgranen is the general word: any kind of boxed breakfast cereal.

You can also use more specific words:

cornflakes – actual English loanword, widely used.
muesli
cruesli (brand-based word for crunchy muesli-like cereals)

So depending on context:

Zij heeft ontbijtgranen gekocht. – She bought cereal (in general).
Zij heeft cornflakes gekocht. – She bought cornflakes (specifically).

In the given sentence, ontbijtgranen is natural because we don’t care about the exact type.

Why is it de doos and not het doos?

Dutch has two grammatical genders for nouns that affect the article:

de-words (common gender)
het-words (neuter gender)

Doos (box) happens to be a de-word:

de doos – the box
een doos – a box

There is no rule you can deduce just from the English “box”; you have to learn each noun’s gender. But many concrete objects ending in -s are de-words (e.g. de tas – the bag, de bus – the bus, de doos – the box).

What does dus do here, and why is there a comma before it?

dus means “so / therefore”. It introduces a result or consequence:

Het is een week geleden dat zij ontbijtgranen heeft gekocht, dus de doos is bijna leeg.
= It’s been a week since she bought cereal, so the box is almost empty.

About the comma:

In Dutch, when dus connects two seperate main clauses, a comma is usually written before it, just like with maar (but), want (because):
- … heeft gekocht, dus de doos is bijna leeg.

Spoken, you’d naturally pause there, which the comma represents in writing.

Could the word order be … dus is de doos bijna leeg instead of … dus de doos is bijna leeg?

Yes, both are possible, with a slight nuance.

… dus de doos is bijna leeg.
- dus acts more clearly as a conjunction linking two main clauses.
- Very common in writing and speech.
… dus is de doos bijna leeg.
- Here dus behaves a bit more like a sentence adverb at the start of a new main clause, and you then apply normal V2 word order (is in second position).
- This can sound slightly more emphatic or rhetorical, especially in spoken language.

Both are understood as:

… so the box is almost empty.

In neutral style, … dus de doos is bijna leeg is perfectly natural and perhaps the most straightforward.

Why is it bijna leeg and not something like bijna is leeg?

Leeg is an adjective used as a predicate after the verb zijn (“to be”):

De doos is leeg. – The box is empty.

Bijna is an adverb that modifies leeg:

bijna leeg – almost empty

So the structure is:

de doos (subject)
is (verb)
bijna leeg (predicate: adverb + adjective)

You cannot separate bijna from leeg or insert a verb in between (bijna is leeg is incorrect). The adjective phrase has to stay together:

✅ De doos is bijna leeg.
❌ De doos bijna is leeg.
❌ De doos is leeg bijna. (very odd)

Could I replace dus with want in this sentence?

You could, but the meaning changes slightly:

Het is een week geleden dat zij ontbijtgranen heeft gekocht, dus de doos is bijna leeg.
– It’s been a week since she bought cereal, so the box is almost empty.
(dus = result)
Het is een week geleden dat zij ontbijtgranen heeft gekocht, want de doos is bijna leeg.
– It’s been a week since she bought cereal, because the box is almost empty.
(want = reason)

The original sentence presents:

fact A: It’s been a week since she bought cereal
conclusion B: therefore, the box is almost empty.

With want, you’d be saying the empty box explains why you say “it’s been a week”, which is a bit odd logically. So dus is the appropriate connector here.