Раскройте скобки, постройте предложения в Past Perfect Continuous 1) My sister

Раскройте скобки, постройте предложения в Past Perfect Continuous
1) My sister ... (to practise) for two months before that concert.
2) The boys ... (to fish) for three hours before Tom caught the first fish.

3) We ... (to discuss) that problem for more than an hour before we found the right solution.
4) Tom ... (to wait) for half an hour before he saw his girlfriend getting off the tram.
5) Driving to the hospital was difficult as it (to snow) all night.
6) David ... (to study) economy since she entered university.