formal source

例句：

1. 1. The formal source of the information was a government report.
   该信息的来源是一份政府报告。
2. 2. The official source confirms that the incident occurred at the designated location.
   官方来源确认事件发生在指定地点。
3. 3.The formal source of the data is from a reliable database.
   数据的正式来源来自一个可靠的数据库。