例句：

　　Diamonds are the hardest known mineral.

　　鉆石是已知的最堅硬的礦石。

　　It must be stated that this illness is one of the most complex conditions known to man.

　　必須聲明，這種疾病是人類已知的最為復(fù)雜的疾病之一。

　　She is best known for her work on the human brain.

　　她在對人腦的研究方面最為知名。

　　Had I known that I would never have come.

　　要是早知道，我絕不會來的。

　　I haven't known him as long as you.

　　我認識他的時間沒有你長。