Past perfect continuous vs. Past continuous

We _____ (wait) for the bus for hours when it finally arrived.

• were waiting

• had been waiting

Last Monday, at 8 am, I ____ (eat) my breakfast.

• was eating

• had been eating

They ____ (walk) home when suddenly it started to rain.

• were walking

• had been walking

We ____ (live) there for months before we finally met in the neighborhoood.

• were living

• had been living

Nick ___ (listen) to the radio when someone knocked on the door.

• was listening

• had been listening

When I arrived at the party, my friends ____ (dance) for two hours.

• had been dancing

• were dancing

She ____ (study) when the power went out.

• was studying

• were studying

He was exhausted because he ___ (run) all morning.

• was running

• had been running