But first, after 18 consecutive days of talks in Vienna and after a month of tense, detailed negotiations, a deal was finally hammered out on Monday between Iran and six world powers on curbing Iran's nuclear programme in return for the lifting of sanctions. 

翻译：

首先，经过了在维也纳连续18天的谈话，以及历时一个月激烈而深入细节的谈判，伊朗与6个世界大国于本周一达成了一项关于伊朗核计划的协议，作为撤销对其制裁的条件。