on the tip of your tongue: you know something, but you just can't quite remember it at the moment. 指你知道某事，但某个时刻突然就记不起来，通常说的“就在嘴边儿，马上就想起来了”；也可表示适时地阻止，停止（说出某个消息）
The name was on the tip of my tongue, but I just couldn't make the connection.
Her name is on the tip of my tongue. Just give me a minute, I'll remember it.
I had the answer on the tip of my tongue, but couldn't think of it in time.
`What do you make of it?' he said after a while. It was on the tip of my tongue to tell him he'd have to ask Charlie. But I said nothing.