a bone of contention

基本解释

Media freedoms have also been a bone of contention .
媒体自由也是一个争论的焦点。
A bone of contention was the division of powers between the national and provincial governments.
争论的焦点，争端争论的焦点是是中央和省政府之间的权力分配问题。
Ingria – the northwestern tip of today’s Russia on which St Petersburg now stands – had been a bone of contention between the two countries for centuries, having passed back and forth between them.
茵格利阿——今天俄罗斯领土的西北端，圣彼得堡的所在地——在几个世纪里一直是两国争端的焦点，而所属权也在两国间来回交替。

The PKK has long been a bone of contention between both sides and prevented economic cooperation.

Before the border became a bone of contention, Alemu's family used to move freely across it.
ECONOMIST: Ethiopia's divided families
North Korea would probably need outside help to make a uranium weapon, but its missile sales—also a bone of contention with America—have won it friends in strange places.
ECONOMIST: North Korea
Yet a bone of contention remains: Government investigators who'd visited the farm in Suffolk said hygiene standards were lax, with uncovered vents and gulls taking meat from open waste bins.
FORBES: U.K. Parliament Cries 'Fowl' Over Turkey Cull Payout

something that two or more people argue about strongly over a long period of time