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
网友回答
(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。