轴承套圈的磨削裂纹历来是轴承生产厂家感到最棘手的问题。
有的时候，即使是最两难的矛盾，当我们由系统的观点看来时，便会发现它们根本不是什么矛盾。
1·The knottiest problem will be what to do with those who cannot be prosecuted but cannot sensibly be freed—and are still dangerous.
最棘手的问题将是如何处置那些不能被起诉，但危险度很高不能轻易释放的那些人。
2·It has became the knottiest problem for parents to deal with their children's "problem behaviors" in the course of growing up.
如何处理孩子成长过程中的“问题行为”已成为许多父母最感棘手的问题。
3·Unemployment, being the knottiest issue of all, has been relegated for now to the back burner.
失业是最棘手的问题，暂时已搁置起来，以后。