One day Tom and I were walking down the street while we saw an old man fall off his bike.

One day Tom and I were walking down the street while we saw an old man fall off his bike. He was badly hurt. Many people crowded around us. Someone suggested carrying the old man to the roadside, so Tom disagreed. He has learned first aid. He said that they ought to leave him where he was and checked him first. At that time the old man wasn't breathing. Tom asked me to call in the First Aid Center at once and he began to start the old man's breathing, use the mouth-to-mouth way. Within five minutes, the old man began to move little and doctors also arrived. They said that we had done was correct. I have learned from this experience that a knowledge of first aid can make a really difference.while—when   us—him    so-but   has-had   checked-check   call in 去掉use-using