CET-4 is divided into oral part and written part. You don't have to take the oral test to take the written test, but you need to take the written test first. There is no limit to the written test scores. Although the official has not indicated that it is necessary to take CET-4, considering the long-term development, there are still many benefits to taking CET-4. First of all, you can know your oral English level, and realize the shortcomings, which can be improved in future study.