Learn Farsi: دانشجوها در کتابخانه بودند.

The base for the past tense of the verb 'to be' is būd. Because the subject is 'students' (a 'they' plural), we add the 'they' ending -and to the base. This gives us būdand.

Why does dāneshjūhā (students) end in -hā?

The suffix -hā is the most common way to make a word plural in Farsi. Here, we add it to the singular noun dāneshjū (university student) to make it mean 'students'.

Could dar also mean 'at' the library?

Yes, Farsi uses the preposition dar for both 'in' and 'at'. So dar ketābkāne can translate to either 'in the library' or 'at the library' depending on what sounds best in English.

The word for library is ketābkāne. Is that a compound word?

Yes! It is made up of ketāb (book) and khāne (house or room). Farsi combines words like this very often, so a library is literally a 'book house'.