You eat so little. No wonder you are so slim.
Are you a librarian? No wonder you are so well read.
There is something wrong with your leg? No wonder you walk so slowly.
A: Is there something wrong? You look so sad.
B: My house was robbed last night and the thieves stole all my furniture.
A: No wonder you look so upset.
B: Yeah. I called the police but they said there was little they could do.
A: Why not?
B: Because there were no witnesses and the thieves didn’t leave any traces.