:to deal with or learn about only a small part of something仅触及表面;浅尝辄止
If you think she only did it for the money, you haven't even scratched the surface. [=there are many other factors, reasons, etc., involved]如果你认为她这么做仅仅是为了钱,那你连问题的皮毛都没看到。
There's so much to learn about this subject. I feel like I've only scratched the surface.关于这个话题有太多需要了解的地方。我觉得我只触及了皮毛而已。