Όταν διαβάζω κείμενο, υπογραμμίζω τις λέξεις που δεν ξέρω.

When I read a text, I underline the words I don’t know.

Breakdown of Όταν διαβάζω κείμενο, υπογραμμίζω τις λέξεις που δεν ξέρω.

• δεν: not
• ξέρω: to know
• διαβάζω: to read
• που: that
• όταν: when
• η λέξη: the word
• το κείμενο: the text
• υπογραμμίζω: to underline

Questions & Answers about Όταν διαβάζω κείμενο, υπογραμμίζω τις λέξεις που δεν ξέρω.

What exactly does Όταν mean here, and how is it different from αν?

Όταν introduces a time clause and means when (in the sense of “whenever / every time that” or “at the time that”).

• Όταν διαβάζω κείμενο = When(ever) I read a text…
• It answers the question “At what time / under what temporal condition?”

Αν means if and introduces a condition, not a time:

• Αν διαβάζω κείμενο… would mean “If I am reading a text…” (a conditional situation), which would sound wrong in this habitual context.

So:

• Use όταν for time: when I do X, I do Y.
• Use αν for condition: if X happens, Y happens.

Why are the verbs διαβάζω and υπογραμμίζω in the present tense? In English I might say “When I read, I underline,” but could it also refer to the future?

The Greek present tense here expresses a habitual action — something you usually do.

• Όταν διαβάζω κείμενο, υπογραμμίζω…
  = “When I read a text, I underline…” / “Whenever I read a text, I underline…”

This pattern ( όταν + present ) is often used for general, repeated actions, even if in English you might think of them as “whenever I’m reading” or “whenever I happen to read”.

For specific future occasions, Greek normally does not use the future tense directly after όταν. Instead it uses the subjunctive with να and then a future verb in the main clause, e.g.:

• Όταν διαβάσω το κείμενο, θα υπογραμμίσω τις άγνωστες λέξεις.
  = “When I (have) read the text, I’ll underline the unknown words.”

So:

• Present after όταν → general/habitual.
• να
  • aorist (perfective) after όταν → a specific future event.

Why is there no article before κείμενο? Shouldn’t it be ένα κείμενο (“a text”)?

Both are possible:

• Όταν διαβάζω κείμενο…
• Όταν διαβάζω ένα κείμενο…

The version without the article is very common in Greek for indefinite or generic objects in habitual statements. It has a slightly more “general” feel:

• διαβάζω κείμενο ≈ “I read (some) text / I’m engaged in reading text.”
• διαβάζω ένα κείμενο ≈ “I read a (particular) text.”

In many habitual or generic sentences, Greek comfortably drops the indefinite article:

• Πίνω καφέ. = I drink coffee.
• Τρώω ψάρι. = I eat fish.

So διαβάζω κείμενο fits that same pattern.

Why is κείμενο singular? In English I might say “When I read texts, I underline the words I don’t know.”

Greek often uses the singular in a generic sense where English prefers a plural:

• Όταν διαβάζω κείμενο…
  ≈ “When I read (a) text / When I read texts in general…”

You could say Όταν διαβάζω κείμενα, which also works and sounds a bit more explicitly plural (“texts”), but the singular is very natural and a bit more abstract.

Think of it as “When I’m in the activity of reading text, I underline the words I don’t know.”

What is the form τις λέξεις exactly? Why τις and not οι?

Λέξη is a feminine noun:

• singular: η λέξη
• plural: οι λέξεις

In this sentence, λέξεις is the direct object of υπογραμμίζω (“I underline”), so it must be in the accusative case (plural feminine):

• οι λέξεις (nominative, subject)
• τις λέξεις (accusative, object)

So:

• Οι λέξεις είναι δύσκολες. = The words are difficult. (subject → nominative)
• Υπογραμμίζω τις λέξεις. = I underline the words. (object → accusative)

That’s why we see τις λέξεις here.

What is που doing in τις λέξεις που δεν ξέρω? Is it like “that” or “which” in English?

Yes. In modern Greek, που functions as a relative pronoun / conjunction connecting a noun to a relative clause, much like that / which / who in English.

• τις λέξεις που δεν ξέρω
  = “the words that I don’t know”

Important points about που:

• It is invariable: it does not change for gender, number, or case.
• It’s very common and often replaces older forms like οι οποίες, τις οποίες, etc. in everyday speech.

So που here simply introduces the relative clause δεν ξέρω and links it to τις λέξεις.

Why is it δεν ξέρω and not something like δεν γνωρίζω? Is there a difference?

Both ξέρω and γνωρίζω can mean to know, but they differ in register and nuance:

• ξέρω is the everyday, neutral verb for “to know”:
  
  • Δεν ξέρω αυτές τις λέξεις. = I don’t know these words.
• γνωρίζω is more formal or can suggest “to be acquainted with / to be familiar with”:
  
  • Γνωρίζω αυτόν τον συγγραφέα. = I’m familiar with this author.
  • In very formal style it can replace ξέρω, but in speech ξέρω is far more frequent.

In this casual, personal-habit sentence, δεν ξέρω is exactly what a native speaker would say.

Could the word order be different? For example, can I say Όταν διαβάζω κείμενο, τις υπογραμμίζω τις λέξεις που δεν ξέρω?

Greek word order is quite flexible, and several variations are possible, but some sound more natural than others.

Here are some acceptable options:

• Όταν διαβάζω κείμενο, υπογραμμίζω τις λέξεις που δεν ξέρω. (your original)
• Όταν διαβάζω κείμενο, τις λέξεις που δεν ξέρω τις υπογραμμίζω. (emphasis on “the words I don’t know”)
• Τις λέξεις που δεν ξέρω τις υπογραμμίζω όταν διαβάζω κείμενο. (emphasizes the object even more)

Repeating τις in front of υπογραμμίζω (a clitic object pronoun) is a common way to emphasize or topicalize the object.

Your suggested version Όταν διαβάζω κείμενο, τις υπογραμμίζω τις λέξεις που δεν ξέρω is grammatical, but it’s more natural to keep τις λέξεις που δεν ξέρω together, then repeat τις:

• …τις λέξεις που δεν ξέρω τις υπογραμμίζω.

Why is there a comma after κείμενο?

The comma marks the boundary between the subordinate clause introduced by όταν and the main clause:

• Όταν διαβάζω κείμενο, → time clause
• υπογραμμίζω τις λέξεις που δεν ξέρω. → main clause

In Greek, it is standard to put a comma when a dependent clause (with όταν, αν, επειδή, etc.) comes before the main clause. If you reverse the order, the comma is usually not needed:

• Υπογραμμίζω τις λέξεις που δεν ξέρω όταν διαβάζω κείμενο.

So the comma is a normal punctuation rule here, not something special about this sentence.

What is the difference between διαβάζω and διαβάσω in similar sentences with όταν?

Διαβάζω is the present (imperfective) stem: it focuses on the ongoing or repeated nature of the action.
Διαβάσω is the aorist (perfective) stem used in the subjunctive and focuses on the completion of the action.

With όταν:

• Όταν διαβάζω κείμενο, υπογραμμίζω…
  → General habit, “whenever I read text, I (usually) underline…”

• Όταν διαβάσω το κείμενο, θα υπογραμμίσω…
  → One specific future event, “When I have read the text, I’ll underline…”

So:

• όταν + διαβάζω → repeated / ongoing / habitual.
• όταν + (να) διαβάσω → one-time, complete action, usually linked to a future main action with θα.

What exactly does υπογραμμίζω mean, and are there other common verbs for “underline” or “highlight”?

Υπογραμμίζω literally means “I underline” (I draw a line under something).

Related or alternative verbs:

• τονίζω = I emphasize (often metaphorical, not necessarily with a pen)
• μαρκάρω (informal) = I mark, I highlight
• χρωματίζω / υπογραμμίζω με μαρκαδόρο = I color / highlight with a marker (more descriptive)

In the context of physically drawing a line under unknown words in a text, υπογραμμίζω is the standard and most precise verb.

What does κείμενο mean exactly, and how is it different from words like βιβλίο or άρθρο?

Κείμενο is a general word meaning text — any piece of written language, regardless of type or length.

Compare:

• κείμενο = text (generic)
• βιβλίο = book
• άρθρο = article (e.g. in a newspaper, magazine, website)
• παράγραφος = paragraph
• δοκίμιο = essay
• κείμενο λογοτεχνίας = literary text

So Όταν διαβάζω κείμενο… is purposefully general: whenever you are dealing with any written text (book page, article, exercise, etc.), you underline the unknown words.