用When或while连接以下各组句子
问题描述：
用When或while连接以下各组句子
1.I was walking to school.+I met a friend
_____________________________________________
2.My friend broke his leg.+He was playing football
______________________________________________
3.We were driving into the city.+ We had an accident.
______________________________________________
4.She was leaving the house. +The telephone rang.
__________________________________________________
答
1.when
2.while
3.when
4.when