The city has improved a lot I came here a few years ago.A. for B. since C. before

问题补充：

The city has improved a lot I came here a few years ago.

A. for B. since C. before

答案：

解析：句意：自从我几年前来到这里，城市已改善了很多。A. for因为，由于B. since 自从 C. before在……之前。由句意可看出选B。

考点: 考查连词的用法。