With commercial airplanes we usually use a measure called cost-per ton-mile.

随着商用飞机，我们通常会用一个衡量所谓成本每吨英里。

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The rates (per ton-mile) for grain are second-lowest of any commodity, trailing only coal, White said.

除煤炭外，谷物（按吨英里算）是所有商品中运费最低的一种商品，怀特说。

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So, we're using one kite in 15 mile per hour winds to lift up a three and half ton block, " said Caltech student Emilio Castano."

科技大学生艾米利奥-加斯塔诺说：“我们要用一只风筝在风速为每小时15英里的情况下抬起3吨半重的石块。”

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Wal-Mart and its suppliers cut the world's biggest civilian heavy-truck fleet's diesel use per ton-mile by 38 percent in 2004-08 and aim to halve it by 2015.

CNN: Freeing America from its addiction to oil