(The full set of video courses has 21 episodes, starting from CET-4 and CET-6 basic English grammar knowledge (simple sentence patterns, simple past tense, simple present tense, common future tense, passive voice, attributive clauses, adverbial clauses, etc.), Then it goes to the detailed explanation of key points, inversions, and subjunctive sentences, and finally transitions to the analysis of basic and special long and difficult sentences and the comprehensive application of knowledge of long and difficult sentences.)