改进题：Several attempts have been made through the years to develop

改进题：Several attempts have been made through the years to develop the deposit.

译文：多年来，作了多次努力为发展这个基金。
【正确答案】：改进的译文：多年来，为开采这部分矿床已经作了几次努力。
【题目解析】：p27