Were:

1. Were you able to attend the party last night?
2. They were playing basketball in the park when it started raining.

Weren't:

1. They weren't able to finish the project on time due to technical difficulties.
2. I wanted to go to the concert, but my friends weren't interested.

Was:

1. There was a beautiful sunset over the ocean last night.
2. The last time I visited Paris, the Eiffel Tower was under renovation.