云朵cloud是不可数名词。
cloud：
n.云;云朵;云状物(如尘雾、烟雾、一群飞行的昆虫);阴影;忧郁;焦虑;令人忧虑的事；
v.使难以理解;使记不清楚;使模糊;显得阴沉(或恐惧、愤怒等);看起来忧愁(或害怕、愤怒等);(尤指用无关的话题来)混淆，搅混(问题)
He still has a cloud of suspicion hanging over him.
大家仍然在怀疑他。
The plane climbed until it was clear of the clouds.
飞机爬升直至穿出了云层。
The sky was full of dark masses of clouds.
天空中乌云密布。
A cloud of dust rose as the truck drove off.
卡车开过时扬起一片灰尘。
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