You have mentioned that "clear basics" so what kind of basics we should clear 1. According to syllabus or 2. About everything
Hello,
Clear basics means the basic and normal thing about any topic. Like if you are Science stream students so you can study about the chemistry, biology, physics and mathematics. So if anyone ask you what's the difference between virus and bacteria and you don't know it then your basic is not clear. This is a small example for basic knowledge.
Whenever you have to study try to understand the topic and clear the basic things. Then you can go depth in the chapter.
All the best.