Some of these facts (is/are) incorrect.

Statistics (is/are) among the most difficult courses.

The chances of you being promoted (is/are) excellent.

There (was/were) a Pokémon card stuck to the refrigerator.

Many hours at the driving range (has/have) led us to design golf balls with GPS locators in them.

Discovered in the soil of our city garden (was/were) a button dating from the Civil War dating from the turn of the century.

Every year, during the midsummer festival, the smoke of village bonfires (fills/fill) the sky.

The story performers (was/were) surrounded by children and adults eager to see magical tales.

Neither the teacher nor his students (was/were) able to solve the equation given by the great Mathematician.