We _________ (sleep) for 12 hours when he woke us up.
The sentence is in past continuous tense, so we will use had been sleeping
We had been sleeping for 12 hours when he woke us up.
They ___________ (wait) at the station for 90 minutes when the train finally arrived.
We ____________ (look) for her ring for two hours and then we found it in the bathroom.
I ________ (not / walk) for a long time, when it suddenly began to rain.
How long ___________ (learn / she) English before she went to London?
Frank Sinatra caught the flu because he _________ (sing) in the rain too long.
My dad ________ smoking in the garage.
They were very tired in the evening because they ________ (help) on the farm all day.
I ____________ (not / work) all day; so I wasn't tired and went to the disco at night.
They ________ (cycle) all day so their legs were sore in the evening.