阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。
Everybody in David’s class packed their bags and got ready_____ (go) home last Saturday. Usually David’s mother would fetch him home but that day she was not there, so he walked home by himself.
When he reached home, he knocked on the door as he didn’t bring his keys. _____ (surprising), no one answered the door. He ____ (knock) again when one of his neighbors _____ (name) John called him. He told David his mother was out and invited him to stay in his house till his mother came back. David knew that if his mother _____ (be) at home, she would have answered the door soon. So David went to John’s house and played with him. ____ (stay) in John’s house for a few ____ (hour), David saw his mother came back. They thanked John and his family. It turned out that David’s mother had_____ serious backache so she had to see the doctor.
From this experience, David has learnt that neighbors are people ______ help each other, and that the relationships among neighbors are like ___ (build) a bridge, and that most people have been building a bridge and they will build a good bridge one day.