The paper needs extensive editing, both the format and the contents. 1. The title should present the main message of the paper and be specific. 2. The Introduction should briefly describe the background in the format of a summary, not one-by-one. Look at the similar review papers as examples. 3. Do not describe the methods of the reviewed papers unless they are a topic of the review. 4. Any uncommon abbreviations should be spelled out. For example, what is CPPU? 5. The discussion should consider pros and cons of the reviewed methods and compare them to others (if any).