1. 云[C][U]The sky became suddenly covered with dark clouds.天空突然变得乌云密布.2. (尘埃、烟等)云状物[C][(+of)]3. (移动中的昆虫、鸟等的)一大群[C][(+of)]A cloud of locusts hit the farm.大群蝗虫袭击了...