He is little known as an artist.

　　幾乎沒(méi)人知道他是個(gè)藝術(shù)家。

　　Christopher is commonly known as Kit.

　　克里斯托弗通常被稱(chēng)為基特。

　　I wish we'd known about it beforehand.

　　要是我們預先知道這事就好了。

　　Diamonds are the hardest known mineral.

　　鉆石是已知的最堅硬的礦石。