In my opinion Jack though relatively stubborn was not too difficult .A. to work withB.

问题补充：

In my opinion, Jack, though relatively stubborn, was not too difficult .

A. to work with

B. working with

C. to be worked with

D. worked with

答案：

(答案→)A. to work with

B. working with

C. to be worked with

D. worked with

解析：考查固定句型：分析句子可知though relatively stubborn,是插入语，暂时不看，句型很明显：Sb is +adj+不定式，这个句型的不定式是主动表被动，另外work是不及物动词要加介词with，句意是：在我看来，杰克虽然相对来说很笨，但一起共事不难。选A。