across the ~

布满天空:

Black clouds spread across the sky.

天空布满黑云。

against the ~

映着天空:

The eagle was black against the early morning sky.

在清晨天空的映衬下，这只鹰看起来是黑色的。

beneath/ under a ~

在天空下:

a ship tossing under a darkening sky

在逐渐阴沉的天空下颠簸的船

from/out of the ~

从天空:

A strange object dropped out of the sky.

一个奇怪的物体从天上掉了下来。

in the ~

在空中:

There was a kite high up in the sky.

高高的天空中有一只风筝。