Niner Diyorbek said these words decades ago. However, we ignored it. So, we couldn't make it what we wanted. I highly recommend that you use authentic materials, like Grammar for IELTS, Vocabulary for IELTS and so on. All of them is written by IELTS expert and Multilanguage learner, Pauline Cullen. If you can afford to buy her books, just buy and learn. I strongly believe you will achieve what you need.