The target audience of this tutorial is people who want to spend some time to truly master English. If you are looking for materials such as "Mastering English in 21 Days", "Memorizing 1000 Words in 10 Days", and "Getting English Writing in 10 Days", this guide is not for you. Especially for language learning, the learning cycle is measured in months or years. The sooner you understand that language learning has no skills, the less time and money will be wasted on various materials...