（某人）很了解某人/通晓某件事情

　　to know something or someone well

　　John is very familiar with software development. He’s been working in IT for 20 years.

　　John很了解软件开发。他做IT已经有20年了。

　　I am not very familiar with Han. We’ve just met once.

　　我对Han不是太了解。我们只见过一次。

　　Know 认识(程度可深可浅)

　　Do you know Penny (well)?

　　你认识Penny吗？

　　Acknowledge

　　(通过招手、微笑等) 打招呼/示意

　　I was standing right next to her, but she didn't even acknowledge me.

　　我就站在她身边，但她根本就没有向我打招呼。

　　Be familiar to sb

　　(某事)对某人来讲熟悉

　　似曾相识/见过/听过/闻过

　　The name of the restaurant was not familiar to me.

　　I didn't know the name of the restaurant.

　　这个餐馆的名字我没听过。

　　Acquaintance /??kwe?nt?ns/ n.

　　泛泛之交；熟人

　　I heard about the job through a mutual acquaintance.

　　我是从一个朋友的熟人那了解到这个工作机会的。