Η ακτινογραφία δείχνει ότι δεν υπάρχει σοβαρό πρόβλημα.

Η is the feminine singular definite article, so it means the.

It is there because ακτινογραφία is a feminine singular noun, and the article has to match it in gender, number, and case:

• η ακτινογραφία = the X-ray
• η διάγνωση = the diagnosis
• η εικόνα = the image

Greek articles are used more regularly than English articles, so learners often need to pay close attention to them.

Because Greek nouns have grammatical gender, and ακτινογραφία happens to be feminine.

This is not about biological sex; it is just a grammatical category. Many nouns ending in -ία are feminine, so this ending gives you a useful clue:

• η ακτινογραφία
• η φωτογραφία
• η ιστορία

So the feminine article η is the expected match.

Here it means X-ray in the sense of the X-ray image / radiograph, not the machine.

That is why the sentence says the X-ray shows something:

• Η ακτινογραφία δείχνει... = The X-ray shows...

In English, X-ray can refer to several related things. Greek works similarly, but in this sentence the meaning is clearly the image or result.

Δείχνει is the 3rd person singular present form of the verb δείχνω, meaning to show.

So:

• δείχνω = I show
• δείχνεις = you show
• δείχνει = he/she/it shows

The subject here is η ακτινογραφία, which is singular, so δείχνει is the correct form.

Ότι introduces a subordinate clause and means that:

• δείχνει ότι... = shows that...

So the structure is:

• Η ακτινογραφία δείχνει = The X-ray shows
• ότι δεν υπάρχει σοβαρό πρόβλημα = that there is no serious problem

This is very common after verbs like:

• λέω ότι = I say that
• νομίζω ότι = I think that
• βλέπω ότι = I see that

No. They are different.

• ότι = that
• ό,τι = whatever / anything that

So in this sentence, ότι is correct because it introduces a statement:

• δείχνει ότι δεν υπάρχει... = it shows that there is not...

Compare:

• Πάρε ό,τι θέλεις. = Take whatever you want.

The comma in ό,τι helps distinguish it from ότι.

Because in Greek, you normally do not put a comma before ότι when it simply means that and introduces the content of a verb.

So this is standard:

• Η ακτινογραφία δείχνει ότι δεν υπάρχει σοβαρό πρόβλημα.

This is different from English, where learners sometimes expect punctuation based on how clauses work in English.

Because δεν is the normal word used to negate a finite verb in statements.

Here the verb is υπάρχει, so Greek says:

• δεν υπάρχει = there is not / does not exist

By contrast, όχι usually means no or not in a more independent or emphatic way, not as the standard preverbal negator in a sentence like this.

So:

• Δεν υπάρχει πρόβλημα. = There is no problem.
• Όχι. = No.

Greek does not need a dummy subject like English there.

English says:

• There is no serious problem

Greek says more literally:

• Not exists serious problem

That is why υπάρχει is so common in sentences expressing existence:

• Υπάρχει λύση. = There is a solution.
• Δεν υπάρχει χρόνος. = There is no time.

So δεν υπάρχει is the natural Greek way to say there is no.

Υπάρχει is the 3rd person singular present form of υπάρχω, meaning to exist / to be present / there is.

So:

• υπάρχω = I exist
• υπάρχεις = you exist
• υπάρχει = he/she/it exists, or there is

In this sentence, the thing whose existence is being discussed is σοβαρό πρόβλημα, which is singular, so υπάρχει is singular too.

Because Greek often leaves out the indefinite article where English would use a.

So:

• σοβαρό πρόβλημα can mean a serious problem
• ένα σοβαρό πρόβλημα can also mean a serious problem

Both are possible, but the version without ένα is very natural, especially in general statements.

This is one of the places where Greek and English article usage do not line up perfectly.

Because σοβαρό has to agree with πρόβλημα, and πρόβλημα is neuter singular.

So the adjective takes the neuter singular form:

• σοβαρός = masculine
• σοβαρή = feminine
• σοβαρό = neuter

Since the noun is:

• το πρόβλημα = the problem

the correct adjective form is:

• σοβαρό πρόβλημα = serious problem

Πρόβλημα is a neuter noun.

A useful clue is the ending -μα, which is very often neuter in Greek:

• το πρόβλημα = the problem
• το γράμμα = the letter
• το μάθημα = the lesson

So in this sentence:

• σοβαρό πρόβλημα

both the adjective and the noun are neuter singular.

Not completely. Greek word order is more flexible than English word order, because Greek shows grammatical relationships through endings as well as position.

This sentence uses a very neutral, natural order:

• Η ακτινογραφία δείχνει ότι...

That said, some parts can move for emphasis. What is much less flexible is the placement of δεν, which normally goes right before the verb:

• δεν υπάρχει

So the sentence feels standard and unmarked as written.

A rough pronunciation guide is:

ee ak-tee-no-gra-FEE-a THEE-khnee O-ti then ee-PAR-khee so-va-RO PRO-vlee-ma

A few helpful notes:

• η sounds like ee
• δ sounds like th in this
• χ is a rough sound, somewhat like German ch or Scottish loch, though it changes slightly depending on the following vowel
• Stress falls on:
  • ακτινογραφία
  • δείχνει
  • υπάρχει
  • σοβαρό
  • πρόβλημα

If you want to sound natural, the rhythm is roughly:

Η ακτινογραφία | δείχνει ότι | δεν υπάρχει | σοβαρό πρόβλημα.