Soon the wool was lying in a terrible tangle all over the carpet, with the kitten running after its own tail in the middle.

running after its own tail in the middle作动名词短语修饰kitten？

with the kitten是介词短语？

【翻译】很快，这团毛线就纠缠不清地散落在整个地毯上，小猫在毛线中间追逐着自己的尾巴。

【分析】with the kitten running after its own tail in the middle 是含有with 的独立主格结构，亦叫 “with 复合结构”，构成：with + 逻辑主语 + 现在分词。其中，running after its own tail in the middle 是现在分词短语，the kitten为其逻辑主语。

with the kitten 不再单独划分，不能看作介词短语，with 在此结构中只起引领作用。