Clauses of Reason
Paul was an hour late. He missed the train. (because)
Paul was an hour late because he missed the train.
Because he missed the train, Paul was an hour late.
I borrowed your lawn mower. You weren’t using it. (as)
I borrowed your lawn mower as you weren’t using it.
As you weren’t using it, I borrowed your lawn mower .
We had no electricity during the storm. We had to use candles. (since)
Since we had no electricity during the storm, we had to use candles.