东北野战军改为第四野战军，辖四个兵团。

And the northeast field army was renamed the fourth field army comprising4armies.

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野战军以下辖兵团，兵团辖军(即原来的纵队)，军辖师，师辖团。

A field army was composed of armies, an army of corps (originally called columns), a corps of divisions, and a division of regiments.

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运动战的特点之一，是其流动性，不但许可而且要求野战军的大踏步的前进和后退。

One of the characteristics of mobile warfare is fluidity, which not only permits but requires a field army to advance and to withdraw in great strides.

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