----If a new difficulty what would we do ?-----Don’t hesitate to turn to us .A. is arise

问题补充：

----If a new difficulty , what would we do ?

-----Don’t hesitate to turn to us .

A. is arisen

B. will be arisen

C. arose

D. would arise

答案：

A. is arisen

B. will be arisen

(答案→)C. arose

D. would arise

解析：句意：如果新的困难出现了，我们该怎么办？--不要迟疑向我们求助。从what would we do ?可知这是和将来相反的虚拟语气的主句，从句应该用过去时或should do，were to do，所以选C。