1) We got a taxi so we weren't late.(If we hadn't a taxi, we would have been late.)
2) I bought new glasses because i broke my old ones.
3)Jane's exhausted so she won't go to the party.
4) The dog got out because Harry had left the door open.
5) I can't find his number so i can't call him/
6) They fell off their bikes because the road was icy.
7) We didn't realise you were coming so we didn't wait.
8) You feel tired because you don't get enough sleep.