During the ten—day vacation they traveled to France their own expenses . AonBwithC

问题补充：

During the ten—day vacation , they traveled to France their own expenses .

Aon

Bwith

C. at

Din

答案：

A. on

B. with

(答案→)C. at

D. in

解析：at one’s own expense是固定搭配，意思是：某人自己出钱（费用）。