Μπορείτε να μου πείτε αν η είσοδος του κτιρίου μένει ανοιχτή μετά τις δέκα;

Yes. Μπορείτε means you can or can you depending on context.

Here it is being used in a polite question:

• Μπορείτε να μου πείτε... = Can you tell me...

A few useful points:

• μπορώ = I can
• μπορείς = you can (singular, informal)
• μπορείτε = you can (plural or singular polite)

So this sentence is addressed either:

1. to more than one person, or
2. politely to one person, like English Could you... / Can you...

να is a very common Greek particle that introduces a subordinate verb, often similar to English to or sometimes a clause like that.

In this sentence:

• Μπορείτε να πείτε literally works like You can tell

So:

• Μπορείτε να μου πείτε = Can you tell me

Important: after verbs like μπορώ (can), Greek uses να + another verb:

• Μπορώ να έρθω = I can come
• Μπορείς να βοηθήσεις = You can help
• Μπορείτε να μου πείτε = Can you tell me

It does not function exactly like the English infinitive to tell, because Modern Greek does not really use an infinitive in the same way English does.

μου means to me.

So:

• πείτε = say / tell
• μου πείτε = tell me / say to me

Greek often uses a weak object pronoun before the verb:

• μου = to me / my
• σου = to you / your
• του / της = to him / her / his / her

Examples:

• Μου λες; = Are you telling me?
• Μπορείτε να μου πείτε; = Can you tell me?

So the word order is very natural Greek:

• να μου πείτε not
• να πείτε μου

Because after να, Greek uses a different verb form from the ordinary present indicative.

The verb is λέω = I say / I tell.
Its forms include:

• λέτε = you say / you are saying
• πείτε = the form used here after να, and also as the plural/polite imperative say!

So in:

• Μπορείτε να μου πείτε... the form πείτε is the correct one after να.

This is one of those verbs where the forms are not fully predictable from the basic dictionary form, so it is worth learning as a chunk:

• να πω = that I say / to say
• να πεις
• να πει
• να πούμε
• να πείτε
• να πουν

Here αν means whether.

So:

• να μου πείτε αν... = tell me whether...

In English, if and whether can overlap:

• Can you tell me if the entrance stays open...?
• Can you tell me whether the entrance stays open...?

Greek uses αν in this kind of indirect yes/no question.

Examples:

• Δεν ξέρω αν έρχεται. = I don’t know if / whether he is coming.
• Πες μου αν είναι ανοιχτό. = Tell me if / whether it is open.

So in this sentence, αν does not mean a condition like if X happens, then... It introduces the embedded question.

This means the entrance of the building or more naturally the building entrance.

Breakdown:

• η είσοδος = the entrance
• του κτιρίου = of the building

This is a genitive construction:

• του = of the
• κτιρίου = genitive form of κτίριο (building)

So:

• η πόρτα του σπιτιού = the door of the house
• το παράθυρο του δωματίου = the window of the room
• η είσοδος του κτιρίου = the entrance of the building

Greek often uses this noun + genitive structure where English might prefer a noun used adjectivally:

• building entrance
• car door
• office manager, etc.

Yes. κτιρίου is the genitive singular form of κτίριο (building).

The noun κτίριο is neuter:

• nominative singular: το κτίριο
• genitive singular: του κτιρίου

This is very common for neuter nouns ending in -ο or -ιο.

Examples:

• το βιβλίο → του βιβλίου
• το δωμάτιο → του δωματίου
• το κτίριο → του κτιρίου

So του κτιρίου literally means of the building.

Because μένει ανοιχτή means stays open or remains open, which fits the idea very naturally.

Breakdown:

• μένει = it stays / remains
• ανοιχτή = open (feminine singular)

So:

• η είσοδος μένει ανοιχτή = the entrance stays open

This is slightly different from simply saying:

• είναι ανοιχτή = it is open

Compare:

• Η πόρτα είναι ανοιχτή. = The door is open.
  (state)
• Η πόρτα μένει ανοιχτή όλη νύχτα. = The door stays open all night.
  (continues to be open)

Since the sentence asks about what happens after ten, μένει ανοιχτή is a very good choice.

Because ανοιχτή has to agree with η είσοδος, which is a feminine singular noun.

Agreement in Greek is very important. Adjectives match the noun in gender, number, and case.

Here:

• η είσοδος = feminine singular
• so the adjective must also be feminine singular:
  • ανοιχτή

Compare:

• η πόρτα είναι ανοιχτή = the door is open
• το παράθυρο είναι ανοιχτό = the window is open
• ο δρόμος είναι ανοιχτός = the road is open

So:

• masculine: ανοιχτός
• feminine: ανοιχτή
• neuter: ανοιχτό

μετά τις δέκα means after ten.

Breakdown:

• μετά = after
• τις δέκα = ten o’clock

Greek commonly uses the feminine plural article τις when telling time:

• στις δέκα = at ten
• μετά τις δέκα = after ten
• πριν τις δέκα = before ten

You can think of it as referring to hours:

• τις δέκα (ώρες)

That is why the article appears even though English just says after ten.

Examples:

• στις τρεις = at three
• μετά τις οκτώ = after eight
• πριν τις έντεκα = before eleven

Because Greek often leaves subject pronouns unstated when the verb ending already shows the person and number.

Here the subject is not a separate pronoun like it; it is the noun phrase:

• η είσοδος του κτιρίου

So:

• η είσοδος του κτιρίου μένει ανοιχτή literally = the entrance of the building stays open

Greek does not need an extra dummy subject pronoun.

Similarly:

• Το κατάστημα κλείνει νωρίς. = The shop closes early.
• Η πόρτα είναι κλειστή. = The door is closed.

English often needs it in some contexts, but Greek usually does not.

The given word order is natural and standard, but Greek is generally more flexible than English.

The sentence:

• Μπορείτε να μου πείτε αν η είσοδος του κτιρίου μένει ανοιχτή μετά τις δέκα;

is a very neutral way to say it.

You might also hear small variations, such as:

• Μπορείτε να μου πείτε αν μετά τις δέκα η είσοδος του κτιρίου μένει ανοιχτή;
• Μπορείτε να μου πείτε αν η είσοδος του κτιρίου είναι ανοιχτή μετά τις δέκα;

The meaning stays similar, but moving elements can slightly change emphasis.

The original puts the time phrase μετά τις δέκα at the end, which is very common and natural.

Yes. Both ανοιχτή and ανοικτή are used and mean open.

In everyday Modern Greek, ανοιχτός / ανοιχτή / ανοιχτό is very common in speech.
Ανοικτός / ανοικτή / ανοικτό is also correct and may sound a bit more formal in some contexts.

So these are both fine:

• Η είσοδος μένει ανοιχτή.
• Η είσοδος μένει ανοικτή.

For a learner, ανοιχτή is probably the form you will hear most often in daily conversation.

You would usually change Μπορείτε to Μπορείς.

So:

• Μπορείς να μου πεις αν η είσοδος του κτιρίου μένει ανοιχτή μετά τις δέκα;

Changes:

• Μπορείτε → Μπορείς
• πείτε → πεις

Everything else can stay the same.

So:

• polite / plural: Μπορείτε να μου πείτε...
• informal singular: Μπορείς να μου πεις...

This is a very useful pattern to learn.