1. As (when) the bell rings, I open the door. On the ringing of the bell, I open the door.
2. As (while) she was writing a letter, the lights went off.
3. When he reaches office, he calls his wife. Soon as he reaches office he calls his wife.
4. When the father comes back home, the children are throwing pillows at one another.
5. While I was watching television, the telephone rang.