The sky was full of dark masses of clouds.

天空中乌云密布。

《牛津词典》

In the western sky, there were great masses of clouds.

西部天空中有大块的云团。

youdao

Before the rain, there were masses of dark clouds in the sky.

下雨前，天空有大片大片的乌云。

youdao

Before the rain, there were masses of dark clouds in the sky.

下雨前，天空有大片大片的乌云。

youdao