Firstly, the research area is divided into three districts according to the physiognomy and the terrain: the northwest low mountainous area, north hilly area and northeast low mountainous area.

首先在空间上依据地形、地貌划分出三个区域：西北部低中山区、北部丘陵区和东北部低中山区。

youdao

Near the eastern horizon, the sky turned a pearly gray, but to the northwest, clouds hung low and threatening.

东方地平线上的天穹出现了灰白色，而西北方却乌云沉沉、步步进逼。

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Heap leaching to low grade gold ore in the Northwest District has been proven a profit making method.

采用堆浸法处理低品位金矿石，在西北各主要产金省已取得了很好的经济效益。

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They burned the captured supplies. Then they moved a few kilometers away to a long, low hill just northwest of the Bull Run battleground, where southern forces defeated a northern army a year before.

VOA: special.2009.09.24

Today the new manufacturing techniques have brought Northwest's tool prices to within 15% of the low-cost Asian competitors.

FORBES: A Savior From the East

The Federal Aviation Administration closed the low-level airspace above roughly four miles in northwest Greater Boston as the search goes on.

WSJ: Boston Bombing Suspect Killed in Shootout

The agency model for plane tickets is very low-margin and is getting squeezed further by mergers in the airline business (Northwest-Delta, United- Continental, Southwest-AirTran).

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