Χτυπάω την πόρτα, αλλά κανείς δεν ανοίγει.

Both are correct. Χτυπάω and χτυπώ are two accepted present-tense forms of the verb χτυπάω / χτυπώ (to hit, knock).

• χτυπάω is very common in everyday spoken Greek.
• χτυπώ is also standard, and may sound a little more concise or slightly more formal in some contexts.

So:

• Χτυπάω την πόρτα
• Χτυπώ την πόρτα

both mean the same thing.

Because in Greek, the verb χτυπάω can take the door directly as its object.

English says:

• I knock on the door

But Greek naturally says:

• Χτυπάω την πόρτα
• literally: I knock the door

This is just a normal difference between the two languages. Greek does not need a preposition here.

Because την πόρτα is the direct object of the verb χτυπάω.

The noun is:

• η πόρτα = the door (nominative, dictionary form)

But after a transitive verb like χτυπάω, the direct object usually goes in the accusative:

• την πόρτα = the door (accusative)

So:

• Χτυπάω την πόρτα = I knock on the door

Here, την is the feminine singular accusative form of the definite article.

Greek uses the definite article much more often than English.

In this sentence, την πόρτα sounds natural because we mean a specific door: the door I’m knocking on.

• χτυπάω την πόρτα = natural
• χτυπάω πόρτα = not natural in this meaning

So even if English sometimes leaves things less specific, Greek often prefers the article when a concrete, identifiable object is involved.

Here, κανείς means nobody.

So:

• κανείς δεν ανοίγει = nobody opens

However, κανείς can also behave like anybody / anyone depending on context, especially in questions or with negation.

For example:

• Είναι κανείς εδώ; = Is anybody here?
• Δεν είδα κανέναν. = I didn’t see anybody / nobody

So the exact meaning depends on the sentence.

Yes, and that is normal in Greek.

Greek commonly uses negative concord, which means several negative words can appear together in the same sentence without canceling each other out.

So:

• κανείς δεν ανοίγει

literally looks like nobody not opens, but it simply means:

• nobody opens

This is standard Greek grammar.

The same thing happens in other sentences too:

• Δεν βλέπω τίποτα. = I don’t see anything
• Κανείς δεν ήρθε. = Nobody came

So a native English speaker should not try to avoid this pattern. In Greek, it is the correct pattern.

Because the subject is κανείς (nobody), which is grammatically third person singular.

The verb ανοίγω (to open) changes like this in the present:

• ανοίγω = I open
• ανοίγεις = you open
• ανοίγει = he/she/it opens

So:

• κανείς δεν ανοίγει = nobody opens

Even though κανείς refers to people, the verb stays singular.

It is the present tense, and in Greek the present tense can cover both:

• I knock
• I am knocking

depending on context.

So:

• Χτυπάω την πόρτα, αλλά κανείς δεν ανοίγει.

could be understood as:

• I knock on the door, but nobody opens
• I’m knocking on the door, but nobody is opening

English often makes a stronger distinction between simple present and present continuous. Greek often uses the same present form for both.

If you want to make the ongoing action especially clear in Greek, context usually does the job.

Yes, both αλλά and μα can mean but.

In this sentence:

• Χτυπάω την πόρτα, αλλά κανείς δεν ανοίγει.

αλλά is a very standard, neutral choice.

You may also hear:

• Χτυπάω την πόρτα, μα κανείς δεν ανοίγει.

That is also correct, but μα can sound a bit more literary, emotional, or stylistically marked depending on context.

For everyday learning, αλλά is the safest default.

Yes, Greek word order is more flexible than English, although not completely free.

The given sentence:

• Χτυπάω την πόρτα, αλλά κανείς δεν ανοίγει.

is perfectly natural.

You could also hear variations like:

• Χτυπάω την πόρτα, αλλά δεν ανοίγει κανείς.

This also means but nobody opens.

Both are correct, but the emphasis is slightly different:

• κανείς δεν ανοίγει puts κανείς up front
• δεν ανοίγει κανείς sounds a bit more like nobody opens / no one is opening

Both are common.

The meaning is basically the same: nobody opens.

The difference is mainly one of emphasis and rhythm.

• Κανείς δεν ανοίγει: emphasizes κανείς a bit more
• Δεν ανοίγει κανείς: often sounds slightly more conversational in some situations

A learner should understand both and feel free to use either, though the original version is very clear and standard.

It can mean both.

χτυπάω / χτυπώ has a broad range of meanings, including:

• to hit
• to strike
• to beat
• to knock

So the exact meaning depends on context.

Examples:

• Χτυπάω την πόρτα. = I knock on the door
• Χτύπησε το χέρι του. = He hurt / hit his hand
• Το τηλέφωνο χτυπάει. = The phone is ringing

So it is a very useful everyday verb.

A rough pronunciation guide is:

• Χτυπάω ≈ htyee-PA-o
• την ≈ teen
• πόρτα ≈ POR-ta
• αλλά ≈ a-LA
• κανείς ≈ ka-NEES
• δεν ≈ then (with a soft th as in this)
• ανοίγει ≈ a-NI-yi

A few useful pronunciation notes:

• χ is not like English h. It is a rough sound. Before ι or η, it is softer.
• γ in ανοίγει is not a hard English g here; it sounds more like a soft y-type sound in this combination.
• The written accent mark shows which syllable is stressed:
  • χτυπάω
  • πόρτα
  • αλλά
  • κανείς
  • ανοίγει

Because Greek often leaves out subject pronouns when they are not needed.

The verb ending already tells you the subject:

• χτυπάω = I knock / I am knocking

So Greek does not need to say εγώ unless there is special emphasis.

Compare:

• Χτυπάω την πόρτα. = I’m knocking on the door.
• Εγώ χτυπάω την πόρτα. = I’m the one knocking on the door. / I am knocking on the door.

So omitting εγώ is normal.

It can do both, depending on context.

The Greek present tense can express:

• something happening right now
• a habitual or repeated action
• a vivid description in narration

So:

• Χτυπάω την πόρτα, αλλά κανείς δεν ανοίγει.

most naturally suggests something happening now, but grammar alone does not force that interpretation as strongly as English sometimes does.

Context tells you whether it means:

• I’m knocking on the door, but nobody is opening or
• I knock on the door, but nobody opens

Yes. In full, the idea is nobody opens the door, but Greek often leaves the object understood when it is obvious from context.

So:

• κανείς δεν ανοίγει

naturally means:

• nobody opens
• that is, nobody opens the door

Because την πόρτα was just mentioned, there is no need to repeat it. This kind of omission is very common and natural in Greek.