Learn Hardcore Greek: Πρόσεχε όταν περνάς τον δρόμο, σε παρακαλώ. - Be careful when you cross the road, please.

It’s the 2nd person singular present imperative of προσέχω. It means “be careful” or “keep paying attention.” It implies ongoing attention. Contrast it with Πρόσεξε (aorist imperative), which is more like “pay attention (right now/just once)” or “watch out!”

Why is it όταν περνάς and not something like όταν περάσεις?

όταν περνάς uses the present to express simultaneity or a general, repeated situation: “when(ever) you are crossing.” It focuses on the action in progress.
όταν περάσεις uses the aorist subjunctive and refers to a single future event as a whole, often with a “once/after you’ve crossed” feeling. Example: Όταν περάσεις τον δρόμο, τηλεφώνησέ μου. = “When you cross the road, call me (after you’ve crossed).” In this warning, we want you to be careful during the act, so όταν περνάς is the natural choice.

Could I say όταν θα περνάς for the future?

Colloquially you may hear όταν θα…, but standard modern Greek typically avoids θα after όταν. For a future single event, Greek prefers όταν + subjunctive (e.g., όταν περάσεις). For a general instruction or simultaneity, the present (όταν περνάς) is fine.

Why is it τον δρόμο and not just δρόμο?

Greek normally uses the definite article with countable nouns, even when English wouldn’t. Here τον δρόμο is the direct object (accusative singular masculine) of περνάς. If you wanted “a road,” you’d say έναν δρόμο.

Is τον δρόμο ever pronounced or written as το δρόμο?

In casual speech, many speakers drop the final -ν of τον before most consonants (including δ), so you’ll hear το δρόμο. In careful writing (and often in careful speech), keep τον. The -ν is usually retained before vowels and certain consonants (κ, π, τ, μπ, ντ, γκ, ξ, ψ, τσ, τζ).

What’s the difference between σε παρακαλώ and παρακαλώ?

Both can mean “please,” but:

σε παρακαλώ literally “I beg/ask you,” feels more direct or polite/insistent toward the person addressed.
παρακαλώ can mean “please,” and also “you’re welcome.” You can place σε παρακαλώ at the start or end: Σε παρακαλώ, πρόσεχε… or …πρόσεχε…, σε παρακαλώ. The comma sets it off as a polite tag.

Can I change the word order?

Yes. For example:

Σε παρακαλώ, πρόσεχε όταν περνάς τον δρόμο.
Όταν περνάς τον δρόμο, πρόσεχε, σε παρακαλώ. If you front the όταν-clause, use a comma after it.

Could I use another verb for “cross,” like διασχίζω?

Yes, διασχίζω is “to traverse/cross,” but it sounds more formal. Everyday speech prefers περνάω/περνώ: περνάς τον δρόμο. Be careful with περνάω από (“go through/pass by”): περνάω από τον δρόμο doesn’t mean “cross the road”; it means “go along/by the road.”

How do I pronounce tricky letters here, like χ and δ?

χ in Πρόσεχε is a breathy sound. Before e/i it’s the softer [ç], similar to German “ich.”
δ in δρόμο is a voiced “th” as in “this”: [ð]. Stress: ΠΡΌ-σε-χε, περ-ΝΆΣ, ΔΡÓ-μο.

How do I make this polite/formal or address more than one person?

Use the plural/formal forms:

Προσέχετε όταν περνάτε τον δρόμο, σας παρακαλώ. Here προσέχετε and περνάτε are 2nd person plural, and σας παρακαλώ addresses “you (plural/formal).”

Is the comma before σε παρακαλώ required?

It’s standard to set σε παρακαλώ off with a comma because it functions like a parenthetical “please.” You’ll also see it at the start with a comma after: Σε παρακαλώ, …

Could I replace όταν with καθώς or ενώ?

καθώς = “as/while,” focusing on simultaneity: Πρόσεχε καθώς περνάς τον δρόμο also works well.
ενώ often contrasts two actions (“while/whereas”) and is less neutral here. όταν is the most natural and general for “when.”

Why not just say Πρόσεχε τον δρόμο?

Πρόσεχε τον δρόμο means “Pay attention to the road,” but it doesn’t express the timing “when you are crossing.” The όταν περνάς clause makes it clear the caution applies during the act of crossing.