The Duolingo English Test book is a guide for the adaptive test that assesses the English proficiency level of non-native English speakers. Comparing to other English Proficiency tests, Duolingo English Test (DET) is more is convenient, fast, affordable, and trusted. This book provides a guideline on how to prepare yourself for the test and obtain the best possible score in the DET. The materials used in the book is for practices and the actual test may vary quite a lot, yet the more you practice with this guide, you may get more confidence to obtain a better score.