I finally found that how I can study with grate focus on the main points and how I can study continually. My miracle is studying loudly. It’s better to say that it is possible for me to read a text or although to think about the problem by loud sound ,and do not stop it at all. I can also repeat some sentences by myself about the works that I want to do soon. I am very delighted with discovering the secret for myself;  I suggest this method to someone who wants to study with grate focus and who wants to study for a long time .