Betty was ironing the blouse when she burnt her hand.
As/When/While Betty was ironing the blouse, she burnt her hand.
We were having a picnic when it started to rain.
As/When/While we were having a picnic, it started to rain.
Helen was washing the dishes when she broke a glass.
As/When/While Helen was washing the dishes, she broke a glass.
Matt and Oliver were getting ready to go out when the doorbell rang.
As/When/While Matt and Oliver were getting ready to go out, the doorbell rang.
