关键的问题是，如果没有更全面的英国-欧盟未来关系协议，所谓的爱尔兰障碍（Irish backstop ） — —将阻止在北爱尔兰和爱尔兰共和国之间建立硬边界。
The key problem is the so-called Irish backstop, which would prevent the establishment of a hard border between Northern Ireland and the Republic of Ireland in the absence of a wider deal on the future of UK-EU relations.