The double-lined arrow in the diagram is an alternative notation that shows a unit being hosted on another unit.

图表中的双行箭头是一种提示：寄主于另一个单元上的单元。

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The digester is a tarp covered, double lined lagoon the size of five football fields. A week from now methane will cause the tarp to expand.

消化池是一个由油布苫盖的双内衬污水池，有五个橄榄球场那么大。从现在开始的一周内，甲烷会导致油布膨胀。

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Our men's shirts are packed each in a plastic bag, 5 dozens to a carton which is lined with waterproof paper and secured by double overall metal straps.

我方男衬衫的包装为每件套一塑料袋，5打装一纸箱，内衬防潮纸，外达铁箍两道。

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After Pettitte struck out Desmond Jennings and Ryan Roberts, Zobrist, who improved to 9 for 22 against the left-hander, lined his double to center.

WSJ: Cobb has strong start as Rays beat Yankees 3-0

Just nine days shy of the fifth anniversary of that gem, the left-hander retired the first 17 batters before Izturis lined a clean double several feet over the outstretched arm of third baseman Will Middlebrooks that landed just inside the foul line.

NPR: Lester Pitches 1-Hitter, Red Sox Top Blue Jays 5-0