After Billy proved that he could ride a bicycle safely,his father ___ to him and bought him one.
问题描述：
After Billy proved that he could ride a bicycle safely,his father ___ to him and bought him one.
答
当 Billy 证明 他可以安全的骑自行车之后,他爸爸答应了他并且还买了一辆给他
应该 填 promises
proved 是 证明 的意思