We need to do more than just learn language structure.为什么 learn不加ing.

than前后加的是平行结构,后面加原形还是ING,要根据具体情况,以rather than为例：
接动词不定式 ,后面的to可以省略
1. I decided to write rather than （ to ） telephone.
2. She likes to keep things rather than （ to ） throw them away.
接动名词
1. I always prefer getting up early rather than going to school without breakfast.
2. He enjoys reading rather than watching TV.
（学语言时）我们需要做的更多,而不仅仅是学习语言结构