28． What did people usually do before when they had usedup their films

题目：28． What did people usually do before when they had usedup their films

A． They often bought a new camera．
B． They often bought some new films．
C． They often showed them to their friends．
D． They returned their cameras to the factory．

喵查答案：D

28.D【解析】根据第二段饲数第四句可知。