精通于

例句：

1. 1. She has been studying the language for many years and is now proficient in it.
   她多年来一直在学习这门语言，现在已经非常熟练了。
2. 2. The expert has mastered the technique and can perform the task with ease.
   这位专家已经掌握了这项技术，可以轻松地完成这项工作。
3. 3. The student has become proficient in solving complex problems through practice.
   这个学生通过练习已经熟练掌握了解决复杂问题的技巧。