这个问题千头万绪，三言两语说不清楚。

This problem is too complicated to be explained in a few words.

《新英汉大辞典》

当然，说着容易做着难。要想放下千思万绪而专注于目前必须做的或是想做的是很难的。

Of course, it's much easier said than done to empty your mind of everything and focus on what you have to or want to do at the moment.

youdao

USPTO的主管Jon Dudas说，把事情弄的更糟的是，专利申请案也变得千头万绪：一些申请案中包含了上千个声明。

To complicate matters further, says Jon Dudas, the director of the USPTO, patent applications have become more complex as well as more numerous: some applications contain thousands of claims.

youdao