"They were singing in the church."

Translation: Ei cântau în biserică.

[JonEnMiljon]

So, how is ”la biserică” and ”în biserică” used? I am confused by the multiple choice suggestions... they say I can't use ”la” although I really think I learned that it was correct in previous lessons

[Andra_Iasomie]

"la" is more like "at" and "în" means "in"