1. sentences: introduction
    └─ two sorts
    └─ build a statement
        └─ negative
    └─ build a question
2. verbs: introduction
3. tenses: general
    └─ simple present
    └─ present continuous
    └─ simple past
    └─ past continuous
    └─ present perfect
    └─ present perfect continuous
    └─ simple future
    └─ going to future
4. tense & time
5. and more
    └─ additions
    └─ adjective & adverb