With HSK test papers as its primary source, HSK Standard Course is characterized by a humorous style, familiar topics and a scientific course design. Matching the HSK test in all aspects, from the content, form to the levels, it is a series of new-type course books embodying the idea of "combining testing and teaching, and promoting learning and teaching by testing". It is suitable for the Confucius Institutes in different countries as well as other Chinese teaching institutions and self-taught learners. The whole series is divided into six levels matching the HSK test, with one volume for each of Levels 1-3 and two volumes for each of Levels 4-6, totaling nine volumes. With a textbook, a workbook and a teacher's book in each volume, there are altogether 27 books. This is Textbook 4A, which includes 10 lessons, covering about 300 words (half of the Level 4 vocabulary) and the detailed explanations of 50 language points and 10 groups of confusable phrases.