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

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?