Breakdown of Estes livros são difíceis.
ser
to be
o livro
the book
este
this (este, esta, estes, estas)
difícil
difficult
Questions & Answers about Estes livros são difíceis.
How do we get "difíceis" from the singular word for "difficult"?
The singular word is difícil. In Portuguese, when an adjective or noun ends in -l, you form the plural by dropping the -l and adding -is. So, difícil becomes difíceis. Notice that the accent mark stays on the í to keep the stress on that same syllable.
Does the adjective "difíceis" change if the noun is feminine?
No! Adjectives ending in -l (and their plural forms ending in -is) are gender-neutral. They look the exact same for masculine and feminine nouns. If we were talking about feminine things, like questions, we would still say Estas perguntas são difíceis.
Why use "estes" instead of "esses" for "these"?
Estes specifically means "these" (objects physically close to the speaker). Esses means "those" (objects close to the person you are speaking to, or just slightly further away). Because the English translation says "These books", estes is the correct match.