1)Jim was absent from class yesterday.he was suffering from a bad cold

=> Jim was absent from class yesterday because he was suffering from a bad cold.

2)They decided to move their house.they don't have to travel a long distance to work

=> They decided to move their house so (so that) they don't have to travel a long distance to work

3)mary hurt her fingers yesterday.she was preparing dinner

=>Mary hurt her fingers yesterday while(when) she was preparing dinner

4)At 4pm yesterday,my mother was cleaning the house.I was looking after my younger brother

=> At 4pm yesterday, my mother was cleaning the house while I was looking after my younger brother.

5)They decided to go an excursion.They want to get away from work stress

=> They decided to go an excursion since/because they want to get away from work stress.

6)my father taught me how to use the computer.before that, I did't know how to use it

=> I didn't know how to use the computer until my father taught me how to use it

7)I arrive at the station.I will call you right after that

=> I will call you as soon as I arrive at the station.

8)My brother is very out-going.I am quite reserved

=> My brother is very out-going but I am quite reserved.