in addition to 的意思是“除…外(还)”，其中的 to 是介词，所以后接动词时，所接动词必须用动名词，不能用动词原形。又如：

In addition to learning English, he has to learn a second foreign language. 除了学习英语之外，他必须学习第二外语。

In addition to giving a general introduction to computers, the course also provides practical experience. 课程除了大致介绍电脑知识外，还提供实际操作的机会。

In addition to lending me his typewriter, he taught me how to use it. 他不仅把打字机借给了我，而且还告诉我如何用。