Past Perfect Continuous КС-21

My sister … (to practise) for two months before that concert.

The boys … (to fish) for three hours before Tom caught the first fish.

We … (to discuss) that problem for more than an hour before we found the right solution.

Henry … (to wait) for half an hour before he saw his girlfriend getting off the tram.

Driving to the hospital was difficult as it … (to snow) all night.

Polly … (to study) economy since she entered university.

Ron’s collection of coins was valuable as he … (to collect) them since he was a schoolboy.

Tania (not to finish) doing the housework by five o'clock, so she called Nadia to tell her she would be late.

She didn't eat anything at the party because she (already to eat) at home.

David was irritated because the police inspector … (to ask) him questions for more than an hour.

Kevin was exhausted because he … (to unload) the lorry for three hours.

Why did Ed miss his training yesterday? — He couldn’t come because he … (to prepare) his project all day yesterday.