"They have books."
Translation:Eles têm livros.
It should be fine for us to write "Eles têm livros" as well correct? We weren't given any context.
Not in Brazil. In Portugal the letter E in têm may slightly sound longer /teem/
"Elas têm livros" or "eles têm livros" is the same as "they have books" it should be ok both answers
Why did I get marked off for not adding the "Elas". Isn't Portuguese a language (like Spanish and Italian) where the pronoun isn't always necessary?
Not wrong. Just dont forget you have (você tem(sing) / vocês têm (pl)).
I think you should always use it before the possessive "Eu tenho os teus livros". (Sorry if I'm wrong!)