Breakdown of Il dottore ha letto le sintesi della ricerca.
avere
to have
di
of, from
il dottore
doctor (male)
leggere
to read
Questions & Answers about Il dottore ha letto le sintesi della ricerca.
How can I tell if sintesi is singular or plural here?
You have to look at the article! Sintesi is a feminine noun of Greek origin ending in -i. These nouns are invariable, meaning their spelling stays exactly the same in both the singular and the plural. Because the sentence uses the plural article le, we know it means the plural "syntheses". If it were singular, it would be la sintesi.
Why doesn't the past participle letto change to match le sintesi?
When a past tense uses the helping verb avere (like ha), the past participle usually stays in its default masculine singular form (letto). It only has to agree with the object if you use a direct object pronoun (like le) before the verb. Since the full noun le sintesi simply comes after the verb, letto does not change.
Is ricerca countable in Italian, unlike the English word "research"?
Why is it della ricerca and not just di ricerca?