答案：B

题目分析：句意：—我的朋友经过多年的努力终于实现了他的目标。—太棒了。有志者事竟成。A. One tree can't make a forest一木不成林；B. Where there is a will, there is a way有志者事竟成；C. Many hands make light work众人拾柴火焰高；D. A friend in need is a friend indeed患难之交见真情。结合第一句的意思可知选B。