cloud是可數名詞還是不可數名詞

　　The plane climbed until it was clear of the clouds.

　　飛機爬升直至穿出了云層。

　　The sky was full of dark masses of clouds.

　　天空中烏云密布。

　　A cloud of dust rose as the truck drove off.

　　卡車開過時揚起一片灰塵。

　　The sun disappeared behind a bank of clouds.

　　太陽消失在一大片云后面。

　　It was beginning to cloud over.

　　天空開始陰云密布。

　　The dark clouds in the sky meant that a storm was coming.

　　天空中的烏云預示暴風雨即將來臨。