Right, it should be "weren't". It is the books that weren't interesting. "books" is plural, so it needs the plural verb.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Ti?u C?mI think ''wasn't" must be "weren't".Yes, you're right! "books" is plural, so we need the verb that goes with "plurals", and in this case, that verb is "were(n't)".