Question

I _____ very surprised because all my books _____ on the floor. *

were // were

was // were

was // was

were // was

was // are

​

Answer 1

Resposta: was/were

Explicação: O verbo to be no passado (vou supor que você já sabe o que é, caso não saiba, me avisa aqui nós comentários e eu explico!) tem duas formas, was e were.

WAS - para o singular

WERE - plural

"I" (Eu) está no singular, então usamos was; "Books" (Livros) estão no plural, então usamos "were".

Espero ter ajudado!