why do i need to include the "i" when im saying "i read books" but not when im saying "they read books"
Depends on if you are talking in english, en english you have always say the subject, but in italian it isn't necessary, you can say a sentence without the subject
Can I say "Loro leggono i libri"?
Does "libri" need the article "i"?
Only when you are talking about one person. For example "Io leggono i libri" ( I read books) you don't need to use "i" when talking about multiple people. For example, "Le donne leggono libri" (The women read books)
I too often read sandwiches.
according to what I heard, the lady said "they read the books" and the answer was "they read books"
I got this wrong because I didn't put a period at the end even though all of the other ones were fine without a period???