Desni krvare, tako da ih stomatolog pregleda.

Here desni is a noun, not the adjective right.

Serbian has the same form desni in different roles:

• as an adjective form of desan / desni = right
• as a noun meaning gums

In this sentence, the context shows it is the noun gums. It is normally treated as a plural noun, which is why the verb is plural too.

Because desni is the subject, and it is plural.

krvare is the 3rd person plural present form of krvariti = to bleed.

So the structure is:

• desni = subject
• krvare = plural verb agreeing with that subject

It can mean either, depending on context.

Serbian does not have a separate present continuous form like English are bleeding. The simple present krvare can cover:

• a general meaning: bleed
• a current situation: are bleeding

So learners should get used to one Serbian present form matching both English patterns.

Tako da introduces a result/consequence clause.

Depending on context, it can be translated as things like:

• so
• so that
• with the result that

In this sentence, it connects the two ideas as cause/result: the gums are bleeding, and as a result the dentist examines them.

Because it separates two clauses:

• Desni krvare
• tako da ih stomatolog pregleda

In Serbian, a comma is normally used before conjunctions that introduce a new clause of this type, including tako da.

Ih is the unstressed pronoun meaning them.

Here it refers back to desni and is in the accusative plural, because the gums are the direct object of pregleda.

So:

• desni = subject in the first clause
• ih = direct object in the second clause

A useful comparison:

• ih = short, unstressed form
• njih = fuller/stressed form, often used for emphasis or after prepositions

Because ih is a clitic.

Serbian clitics usually go very early in the clause, often in the second position. After the conjunction tako da, the natural placement is:

• tako da ih stomatolog pregleda

Not:

• tako da stomatolog pregleda ih

So this is mainly a word-order rule for short unstressed pronouns.

Because Serbian verbs agree with the subject, not the object.

In the second clause:

• stomatolog = subject, singular
• ih = object, plural

So the verb must be singular:

• stomatolog pregleda

not plural.

This also shows that stomatolog is in the nominative singular here, because it is the subject.

Pregleda is the 3rd person singular present form of pregledati.

The important extra point is that pregledati is a perfective verb. That means it presents the action as a single complete examination.

Its imperfective partner is pregledavati, with present forms like pregledava.

Very roughly:

• pregledati / pregleda = examine completely, as one whole act
• pregledavati / pregledava = be examining, examine repeatedly/habitually

So even though pregleda looks like a present-tense form, aspect is doing important work here, and Serbian does not always match English tense choices one-for-one.

Both can mean dentist, but the tone is a little different:

• stomatolog = more formal or medical
• zubar = more everyday and conversational

So stomatolog sounds a bit more professional/clinical. Also, Serbian has no articles, so a bare noun like stomatolog is normal where English would say the dentist or a dentist.