推荐信里这样写一句话合适嘛？求指导！

I do not think that he could find them unless he paid many efforts to read and understand my class materials.
这句话就是说，research中出了一个问题，只有他发现了，不知道这句话会不会显得比较绕？或者不合适呢？
求建议，求指导！