美国有线新闻 CNN 英国脱欧陷入僵局 爱尔兰边界问题成棘手难题（在线收听）

First to international event we're explaining today concerns a breakup. The European Union is composed of 28 European countries. They have an economic and political partnership, but in June of 2016, voters in the United Kingdom decided their country would leave the European Union. This became known as the Brexit, as in British exit from the E.U. It is a very complicated process. For instance, European Union countries trade with each other without tariffs on goods. When Britain leaves the E.U., will it have those taxes reinstated when trading with the rest of Europe?

Immigration, legal decisions, relationships with other countries, all of this has to be worked out, and the deadline for an agreement between Britain and the European Union has been set for March 29. If one is reached, it could mean a smoother transition for Britain in Europe if everyone knows what to expect.

But it has some sticking points. One of them is Northern Ireland. It's part of the United Kingdom and it would leave the E.U. with the rest of Britain while the Republic of Ireland would stay in the E.U. Northern Ireland and the Republic of Ireland are on the same island. Would a hard or controlled border need to be rebuilt between these two sides? There used to be one when there were decades of conflict between them.

A peace deal in 1998 called the Good Friday Agreement led to the open border that you're about to see.

NIC ROBERTSON, CNN INTERNATIONAL DIPLOMATIC EDITOR: This right here is the border between the North of Ireland on this side of the road and the South of Ireland on this side of the road. The road here is quite literally the border. There's no razor wire, there's no checkpoints, there's no customs post here. There is in total between North and South about 310 miles of border and it is crisscrossed by about 300 to 400 different roads.

But Brexit could bring a change to all of that because Theresa May, the British prime minister, has said that Brexit means leaving the European Union, leaving a single market, which throws open the question of what happens to this border?

Twenty years ago, this used to be an army base here. The border just along the road there, and it was one of many army bases that control the border.

A lot of those little lanes that we're looking at there, they were blown off, couldn't be used. That building over there, the army used to that for checking the vehicles, a sort of customs post if you like.

But now, since the Good Friday Peace Agreement that ended the violence, ended the need for the army, this road here, it's opened up again — in fact, to business, if you will. And there's a real economic benefit going on here. This town was beginning to thrive again.

Today, border crossings like this one on the main highway have never been so busy. More than a million vehicles a month crossing over all these borders. One and a half billion dollars worth of trade between Britain and the Republic of Ireland.

No one wants to lose this economic benefit of an open border. The Irish government says that the border should not become hard. The British government, with this negotiation, is in a very difficult position right now. The European Union supports the Irish government, the borders, they want them open for trade.