Sometimes you get information straight from the horse's mouth. 有时,你可以“得到第一手资料”。
It comes directly from the person who knows most about the subject and is the best source. 这个资料信息来源于对该主题事件知道最多的人,是最好的信息来源。
Let us say your teacher tells you there is going to be a test tomorrow. 比如,老师告诉你明天将有一个考试,
You could say you got the information straight from the horse's mouth. 你可以说自己“从马嘴里直接得到了信息”(得到了第一手消息)。
However, you would not want to call your teacher a horse! 然而,你不会去想称呼你的老师为马。