Ser and Estar in Fixed Expressions
Some expressions always use either “ser” or “estar”:
- “Ser cierto” (to be true)
- “Estar seguro” (to be sure)
- “Ser necesario” (to be necessary)
- “Estar de acuerdo” (to agree)
These expressions must be memorized as they don’t always follow the general rules for “ser” and “estar”.