在英文中，晚上天很黑可以用以下几种表达方式来表示：

It's very dark at night.
这是一种直接表达方式，意思是"晚上天很黑"。

It's pitch black at night.
这是一种形容词+副词的表达方式，意思是"晚上天完全黑暗"。"Pitch black"是形容非常黑暗的东西，来源于古英语"pic"，意思是"黑暗"。

It's dark as pitch at night.
这是一种比喻性的表达方式，意思是"晚上天非常黑暗"。"As pitch"是一种修饰语，意思是"像黑胶一样"，来源于古英语"pic"，意思是"黑暗"。

以下是一些例句：

It's very dark at night, so I always carry a flashpght with me when I go out.
晚上天很黑，所以我出门总是带着手电筒。

It's pitch black at night, and I can barely see my hand in front of my face.
晚上天完全黑暗，我几乎看不到自己面前的手。

It's dark as pitch at night, and I'm afraid to go out alone.
晚上天非常黑暗，我不敢独自出门。