Put the verbs in brackets into the Past Simple, the Past

Put the verbs in brackets into the Past Simple, the Past Continuous on Past Perfect Tense.
2.1. / ____________ (to wait) for my sister when _______________ (to start) to rain.
2.2. / suddenly realized that / _________ (to lose) my wallet.
2.3. When they ______________ (to come) to London, they ______________ (to visit) many mu seums.
2.4. Cindy _________________ (to break) her leg while she _______________ (to snowboard).
2.5. Hardly we ____________________ (to finish) dinner when the doorbell rang.
2.6. While we _____________________ (to wait) , we ____________ (to do) crossword puzzles.