It is laid down that all candidates must submit three copies of their dissertation.
根据规定所有的学位答辩人均须提交论文一式三份。
《牛津词典》
2
It is one of only two copies in existence in good condition, and was coined 'the impossible black tulip of cartography' by experts strugging to track it down.
这是仅有的保存完好的两份地图之一，被追溯其踪迹的专家称为制图史上的‘不可能的黑色郁金香’。
3
It is one of only two copies in existence in good condition, and was coined 'the impossible black tulip of cartography' by experts struggling to track it down.