During the drivage of main-gate in long-wall face with fully mechanized caving mining, the gate is hard to support due to its loose and broken roof, large cross-section and long span.

在综采放顶煤工作面顺槽掘进过程中，由于顺槽煤层顶板松动破碎，并且顺槽采用矩形断面，顶板跨距较大，不利于巷道支护。

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When long wall mining to the dip in fully-mechanized coal winning working face is inclined area, we may can't use existing drift draw off water.

当倾斜长壁开采的综放工作面初采范围处于向斜构造区，造成初采放水无法利用已有巷道形成自流放水，必须考虑动力排水或其他的放水方式。

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Long lead times persist for oil drilling rigs, mining equipment and some other specialized machinery, but generally companies face no supply limitations when considering expansion.

FORBES: Economic Forecast Update, 2013-2014: Light-to-moderate Growth