Nothing but some ancient Chinese coins _______ in the sunken ship since they began the exploration. [ ]

A. were found        

B. was found       

C. have been found  

D. has been found

C.证人应当出庭作证，否则其证人证言不能作为定案依据D.经人民法院准许，鉴定人可以不出庭宣读鉴定结论