OG40题在讨论区and hense the bonding作何解没有找到答案

40. In metalwork one advantage of adhesive-bonding over spot-welding is that the contact, and hence the bond­ing, is effected continuously over a broad surface instead of a series of regularly spaced points with no bonding in between.

(A)   instead of

(B)   as opposed to

(C)   in contrast with

(D)  rather than at

(E)   as against being at

答案是D

我的问题是and hence the bond­ing作何解，在句中是什么成份，

看了OG讨论区没有得到解答，谢谢NN们。。

以下是引用清清小蚂蚁在2006-4-2 10:58:00的发言：
carolhide你这么好，这么快的回答，只是AND可以在插入语里放在HENCE前面吗

也许和and yet一样，就是连用的习语呢？不过字典上没查到……

我觉得它表达的是一个递进的意思，所以用了hence这个词。