求翻译：平原是地壳长期稳定、升降运动极其缓慢的情况下，经过外力剥蚀夷平作用和堆积作用形成的。冲积平原主要由河流冲积而成。是什么意思？

Plain long-term stability of the crust, lifting movement is extremely slow in the case, after the accumulation of external erosion leveled the role and the role of the formation. Alluvial flood plain formed mainly by the river.

plains are long-term, stable, and lift the earth's crust movement is extremely slow, crumbling razed role after defeat and accumulation of a role. Mainly by river alluvial bottomlands.

The plain is the earth's crust long-term stability, in the vibratory movement extremely slow situation, levels off the function after the external force disintegration and the accumulation forms.The silting alluviation plain mainly becomes by the fluvial outwash.

Plain is long-term stability, lifting extremely slow movement of the Earth's crust cases, after external force detachment levelling and stacked to form. Main River alluvial flat alluvial becomes.

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