The question is important in the packaging industry where, currently, cardboard boxes can only be flat packed if both their top and their base are left open, You explains.

目前的包装技术只有在箱子顶部和底部都被打开的时候能把他们压平打包，这一点很重要，You解释说。

youdao

For variation, the woman can even lie completely flat, face down on the bed with her legs open, as her partner lies on top of her back, entering from behind.

如果要有所变化，女性可以完全平躺着，面部朝下，双脚打开，由趴在她背部的伴侣从后面进入。

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Heavy rain can quickly wash away the rich top soil on flat, open land.

飘泼大雨能很快地冲走那里的平坦开阔的表层土壤。

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At the very top the flat, a door was open and Shazzia welcomed me with a smile.

BBC: Afghanistan: Through veiled eyes

Near the top, a path broke off and led to a flat open plot, where the castle should have been, but, save for an old stone wall, there were no ruins to be seen.

NEWYORKER: Master of Play