由福建省2001—2006年营运汽车数量的变化和福建省公路总里程的增加及公路密度的增长情况入手，根据欧Ⅰ和欧Ⅱ排放标准估算出2006年营运汽车排放的尾气总量。

We present the change of business vehicle numbers in Fujian during 2001 and 2006, together with the increase of total highway mileage and highway density in the same period.

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它可以实现所需的交通密度，高速公路主线，并能使车辆行驶更安全、更安全。

It can achieve a desired traffic density along the mainline of a freeway, and can make vehicles travel more efficiently and safely.

youdao

写定义交通密度，哪里是公路段的长度。方程(1)现在可以用密度来书。

Define traffic density as, where is length of the road segment. Equation (1) can now be written in terms of density.

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