1. "Sí es" (Yes, it is): This is the most direct opposite, expressing agreement.
2. "Es" (It is): If the original sentence is negative, removing the "no" creates the opposite affirmative statement.
3. "Sí" (Yes): This is a short and simple way to agree with a statement that "no es" contradicts.
Example:
* Original: "No es un libro." (It is not a book.)
* Opposite: "Sí es un libro." (Yes, it is a book.)
* Opposite: "Es un libro." (It is a book.)
* Opposite: "Sí." (Yes.)
It's important to consider the specific context of the sentence to determine the most accurate opposite.