Προτιμώ να διαβάζω λίγες σελίδες κάθε βράδυ, αλλά σήμερα θέλω να διαβάσω ολόκληρο το άρθρο.

This is one of the most important features of Modern Greek verbs: aspect.

• να διαβάζω = to be reading / to read regularly / to read in an ongoing or repeated way
• να διαβάσω = to read once / to finish reading / to read as a complete event

In this sentence:

• Προτιμώ να διαβάζω λίγες σελίδες κάθε βράδυ
  means the speaker prefers this as a habit or repeated action.

• σήμερα θέλω να διαβάσω ολόκληρο το άρθρο
  means the speaker wants to read the whole article as one complete action, probably finishing it.

So the contrast is not really about tense, but about how the action is viewed:

• διαβάζω = ongoing/repeated
• διαβάσω = single complete event

In Modern Greek, να is used before a verb form that often corresponds to English to + verb, or sometimes that + someone verb.

So:

• Προτιμώ να διαβάζω = I prefer to read
• θέλω να διαβάσω = I want to read

A very useful pattern is:

• θέλω να + verb = I want to + verb
• προτιμώ να + verb = I prefer to + verb

Important: Greek does not usually use a separate infinitive like English to read. Instead, it uses να plus a finite verb form.

They express two different ideas:

• Προτιμώ = I prefer
• θέλω = I want

So the sentence contrasts:

• a general preference: I prefer to read a few pages every night
• a specific intention today: but today I want to read the whole article

This is a very natural pairing in Greek:

• προτιμώ often describes what someone generally likes to do
• θέλω often describes what someone intends or desires in a particular situation

Because λίγες must agree with σελίδες in gender, number, and case.

• σελίδα = page
• σελίδες = pages

Since σελίδες is:

• feminine
• plural
• here in the accusative (direct object)

the adjective/quantifier must match it:

• λίγες σελίδες = a few pages

Some related forms:

• λίγος χρόνος = a little time / little time
• λίγη ώρα = a little while
• λίγο νερό = a little water
• λίγοι άνθρωποι = a few people
• λίγες σελίδες = a few pages
• λίγα βιβλία = a few books

Because after κάθε meaning every, Greek normally uses the noun in the singular.

So:

• κάθε βράδυ = every night
• κάθε μέρα = every day
• κάθε εβδομάδα = every week

Even though English also uses the singular here, learners sometimes expect a plural because the meaning is repeated. Greek, however, keeps it singular after κάθε.

Also, βράδυ here is in the accusative form, which is very common in time expressions.

Because σήμερα means today, and it specifies when the speaker has this intention.

The present tense θέλω just means I want right now.
The word σήμερα adds the idea that this desire is true today, in contrast with the speaker’s usual habit.

So the structure is:

• Usually: I prefer reading a few pages every night.
• Today: I want to read the whole article.

This contrast is very natural in Greek, and σήμερα helps signal the change from routine to exception.

Because Greek often uses the definite article when talking about a specific known thing.

• το άρθρο = the article
• ολόκληρο το άρθρο = the whole article

Here the speaker is referring to a particular article, not just any article.

Also note the position:

• ολόκληρο το άρθρο

This is a very common Greek pattern:

• adjective + article + noun

Examples:

• όλο το βιβλίο = the whole book
• ολόκληρη τη μέρα = the whole day
• όλη την εβδομάδα = the whole week

Yes, όλο το άρθρο would also be natural.

Both can mean whole / entire, but there is often a slight nuance:

• όλο = whole, all of
• ολόκληρο = whole, entire, complete

ολόκληρο can sound a bit more emphatic, as if stressing completeness:

• I want to read the entire article

So:

• θέλω να διαβάσω όλο το άρθρο
• θέλω να διαβάσω ολόκληρο το άρθρο

Both are correct and natural.
In many contexts, they are very close in meaning.

Because αλλά means but, and it connects two contrasting clauses.

The sentence has two parts:

1. Προτιμώ να διαβάζω λίγες σελίδες κάθε βράδυ
2. αλλά σήμερα θέλω να διαβάσω ολόκληρο το άρθρο

Just like in English, a comma before but is very common when joining two full clauses.

So this punctuation is normal and helps show the contrast clearly.

It is based on the present stem, but after να it is better to think of it mainly as an imperfective subjunctive-type form, not simply as an ordinary present tense.

For learners, the most practical way to understand it is:

• να διαβάζω = imperfective aspect after να
• να διαβάσω = perfective aspect after να

So instead of focusing only on tense, focus on the contrast:

• ongoing / habitual / repeated
• single / complete

This is why Greek learners often hear that after να, aspect matters a lot.

Because that would sound less natural for a habitual preference.

The first part describes a routine:

• reading a few pages
• every night
• as a general preference

For repeated or habitual actions, Greek usually prefers the imperfective form:

• να διαβάζω

If you said να διαβάσω, it would sound more like:

• to read a few pages as one complete action which does not fit as well with every night and the idea of a regular habit.

So:

• Προτιμώ να διαβάζω... = natural for habits
• θέλω να διαβάσω... = natural for one complete act today

Both are in the accusative case because they are the direct objects of read.

• διαβάζω λίγες σελίδες = I read a few pages
• διαβάσω ολόκληρο το άρθρο = read the whole article

Forms here:

• σελίδες = feminine plural accusative
• άρθρο = neuter singular accusative

In these examples, the accusative tells you what is being read.

A simple pronunciation guide:

• Προτιμώ = pro-ti-MO
• να διαβάζω = na thia-VA-zo
• λίγες σελίδες = LI-yes se-LI-thes
• κάθε βράδυ = KA-the VRA-thi
• αλλά = a-LA
• σήμερα = SI-me-ra
• θέλω = THE-lo
• να διαβάσω = na thia-VA-so
• ολόκληρο το άρθρο = o-LO-kli-ro to AR-thro

A few pronunciation notes:

• δ is pronounced like th in this
• θ is pronounced like th in think
• γ before ε or ι often sounds like a soft y-like sound, so λίγες is not a hard g
• stress matters a lot in Greek, so pay attention to the accented syllable:
  • Προτιμώ
  • διαβάζω
  • λίγες
  • σελίδες
  • σήμερα
  • θέλω
  • διαβάσω
  • ολόκληρο
  • άρθρο

Yes, Greek word order is more flexible than English, though some versions sound more natural than others.

The original sentence is very natural:

• Προτιμώ να διαβάζω λίγες σελίδες κάθε βράδυ, αλλά σήμερα θέλω να διαβάσω ολόκληρο το άρθρο.

You could also hear variations like:

• Σήμερα όμως θέλω να διαβάσω ολόκληρο το άρθρο.
• Αλλά σήμερα, θέλω να διαβάσω ολόκληρο το άρθρο.

Greek often changes word order for:

• emphasis
• rhythm
• contrast

But for learners, the original version is an excellent standard model.