I have jet-black hair.

我有一头黑发。怎样翻译？

The very quirk of a jet-black eyebrow could enforce obedience.

一对乌黑的浓眉似有魔力，能让他人臣服。

She has high nose, jet-black straight hair hang down her waist.

她高鼻梁，乌黑的直发垂下她的腰部。

Many of my own aunts still have jet-black hair even at the age of seventy!

我的许多姑妈仍然拥有墨黑的头发，尽管她们都七十多岁了。

His hair was prematurely white, but his busy eyebrows were still jet-black.

他的头发已经白了，不过两道浓眉还是乌黑乌黑的。