1、the bell ring;watch TV
When the bell rang,we were watching TV.
2、knock at the door;think about the new year
When he knocked at the door,I was thinking about the new year.
3、see him;walk in the street
When I saw him,he was walking in the street.
4、call me;do my homework
When she called me,I was doing my homework.
5、get to school;clean the classroom
When I got to school,they were cleaning the classroom.