1. Though he tried hard, he didn't succeed => However
2. No matter how hard i tried, i couldn't open the door => Try as
3. We stayed in that hotel despite the noise => Although
4. I last saw my uncle when i was a school boy => i haven't
5. His failure bitterly disappointed his parents => his parents
6. why did no one inform me of the change? => why
7.susan felt sick because she caught in the cool=>if
8. i'll find that man no matter how long it takes => however
9. mary isn't used to staying up late => mary finds
10. it's impossible to get a visa to America easily => we find
11. she had only just put the telephone down when the boss rang back => Hardly