Questions & Answers about Il medico studia il virus.
Because Italian uses the definite article much more regularly than English.
- il medico = the doctor
- il virus = the virus
In English, you might sometimes say Doctor studies virus only in special contexts, but in normal Italian you generally need the articles here. So both the subject and the direct object take il.
Because the verb has to match the subject.
The verb is studiare = to study.
Its present tense forms are:
- io studio = I study
- tu studi = you study
- lui/lei studia = he/she studies
- noi studiamo = we study
- voi studiate = you all study
- loro studiano = they study
Since il medico is he/she/it in grammatical agreement, Italian uses the third person singular form: studia.