There being plenty of time left,we needn't be in such a hurr

独立主格结构,主语是we,后面那句是主句,前面那句是从句,原因状语从句相当于
加了since,Since there is plenty of time left,we needn't be in such a hurry.若两个句子间有个and,也就是There is plenty of time left,and we needn't be in such a hurry.