To fill someone in is to erase that emptiness, or that blank, that not knowing can create.

向某人透露消息，是为了消除因为不理解情况导致的信息空缺或空白。

youdao

And it doesn't just have to be about gossip. You can fill someone in on what's been happening in the news, or in a class, or on a TV show.

而且，这些信息不只限于小道消息，还可以包括新闻、班级或电视节目中正在发生的事情。

youdao

Say the story happened to the friend of someone you know, or fill in the specifics with places and names familiar to your audience.

告诉大家故事就发生在你认识的一个朋友身上，或者选择你的听众们都熟悉的地方或者名字作为故事的内容细节。

youdao

It's just the difficulty of getting someone to fill in the paperwork and getting a P.

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Obama's challenge in picking a vice president was to find someone who can fill the holes in his political resume without dampening his charisma and his mantra of change.

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In that case someone else will have to step in to fill the gap.

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