never ⇒ 我不曾见过你。 Wǒ bùcéng jiànguo nǐ. → I've never met you.
曾孙
great-grandson
曾祖
great-grandfather
曾经
once ⇒ 我曾经想出国留学。 Wǒ céngjīng xiǎng chūguó liúxué. → I once wanted to study abroad.
未曾
not ... before ⇒ 我未曾见过他。 Wǒ wèicéng jiànguo tā. → I haven't seen him before.
似曾相识
look familiar ⇒ 他俩初次见面,但却都有似曾相识的感觉。 Tā liǎ chūcì jiànmiàn, dàn què dōu yǒu sì céng xiāngshí de gǎnjué. → It was the first time the two had met, and yet they felt strangely familiar.