乌云密布

The morning began fine, but now clouds are banking up.

早晨开始晴, 现在乌云密布。

The sky blackened and soon it began to rain.

乌云密布, 很快便下起来。

The sky clouded over before the storm.

暴风来临前, 乌云密布。

The sky clouded over; we could see there was going to be rainstorm.

"乌云密布,我们看得出快来暴风了。"

The thick clouds passed overhead, but fortunately the rain kept off the whole day.

虽然乌云密布, 但很幸运地一整都没下。