Полиция проверяет документы на перекрёстке, поэтому движение медленное.

The police are checking documents at the intersection, so traffic is slow.

Breakdown of Полиция проверяет документы на перекрёстке, поэтому движение медленное.

• на: at
• движение: the traffic
• медленный: slow
• поэтому: so
• документ: the document
• проверять: to check
• перекрёсток: the intersection
• полиция: the police

Questions & Answers about Полиция проверяет документы на перекрёстке, поэтому движение медленное.

Why is полиция treated as singular (and why проверяет, not проверяют)?

In Russian, полиция is a singular noun (like the police force as an institution), so it normally takes a singular verb: полиция проверяет.
If you want to emphasize individual officers, you’d typically switch the subject to a plural noun, e.g. полицейские проверяют документы (police officers are checking documents).

What tense is проверяет and does it mean present or future?

Проверяет is present tense of the imperfective verb проверять. In Russian, imperfective present usually means:

• right now / currently: they are checking
• habitually / regularly: they check (in general)

It does not mean future. Future with imperfective uses будет проверять (will be checking). Future with perfective would be проверит (will check / will complete a check).

Why is the verb проверять imperfective here? Could it be perfective?

Imperfective fits because the sentence describes an ongoing process causing slow traffic: the police are in the middle of checking documents.
Perfective would focus on a completed result (one completed check), which doesn’t match the “traffic is slow because this is happening” idea as well:

• Полиция проверяет документы… = ongoing checks
• Полиция проверила документы… = they checked (and finished), so the cause may no longer be happening

Why is документы in the accusative plural, and not some other case?

Проверять takes a direct object in the accusative case. The plural nominative/accusative for inanimate nouns like документы is the same form: документы.
So проверяет (что?) документы = checks (what?) documents.

Does документы here mean “documents” in general, or “IDs”?

In real-life traffic/police contexts, проверять документы often means checking ID / driver’s license / registration papers—whatever documents are relevant. Russian commonly uses the plural документы for that set, even if English might say “ID”.

Why is it на перекрёстке and what case is перекрёстке?

На + location typically takes the prepositional case to mean on/at/in a place.
So на перекрёстке = at the intersection.
The noun перекрёсток changes to prepositional перекрёстке.

What exactly does перекрёсток mean, and is it the same as пересечение?

Перекрёсток is a road intersection (especially where roads cross, often implying a junction with multiple directions).
Пересечение is more general: a crossing/intersection of lines/roads, often in a more abstract or technical sense (e.g., “the intersection of two streets” as a point). For traffic context, перекрёсток is the most natural.

Why is there a comma before поэтому?

Here поэтому introduces a result clause: “therefore / so”. Russian punctuation typically separates the cause and result with a comma:

• Полиция проверяет документы…, поэтому движение медленное.

You can also see поэтому as a connector between two clauses, and the comma marks that boundary.

What’s the difference between поэтому and потому что?

• потому что = because (introduces the reason clause)
  Example: Движение медленное, потому что полиция проверяет документы.
• поэтому = therefore / so (introduces the result)
  Example: Полиция проверяет документы, поэтому движение медленное.

They often form a pair: потому что gives the cause; поэтому gives the consequence.

Why does it say движение медленное (adjective) instead of движение медленно (adverb)?

In Russian, you can describe a noun with a predicate adjective:

• движение медленное = “the traffic/movement is slow” (literally: “movement (is) slow”)

Using an adverb would sound different and is less standard with движение:

• движение медленно is generally not the preferred structure.

A common alternative is to use a verb and adverb:

• движение идёт медленно = traffic is moving slowly
• машины едут медленно = cars are driving slowly

Why is there no word for “is” in движение медленое?

Russian often omits the present-tense form of to be. So:

• движение медленное literally means “movement slow” = “movement is slow”.

You can add это for emphasis/clarity in some contexts:

• Движение — медленное. (more emphatic/contrastive)

But most of the time, the zero-copula (no “is”) is the normal choice.

How do you pronounce перекрёстке, and is ё always written?

перекрёстке is pronounced roughly like pe-ree-KRYOST-kye (stress on ё: крё).
In writing, ё is sometimes replaced by е (so you may see перекрестке), but the pronunciation usually stays ё in this word. In learner materials and careful writing, ё is often kept to avoid ambiguity.