on／at the tip of one's tongue
just going to say话到嘴边
It was on the tip of my tongue to tell him．我差点告诉了他。
It was on the tip of my tongue to call him a liar，but I stopped myself just in time．我差一点叫他为撒谎鬼，但我及时制止了自己。
It's on the tip of my tongue but I still can't remember your name．你的名字就在我嘴边，可我就是想不起来。
He has half a dozen languages at the tip of his tongue．他能随口讲5、6种语言。