Given a word, returns its grading.

• CEFR level
• Frequency

Given a sentence, returns its grading.

• Vocabulary, different types have different weigh (verb, adv, adj will have heavier weigh than nouns.)
• Structure, complex structure vs simple structure.

Given a paragraph, returns its grading. Average grading of sentences.

Given certain sentence, with part of it highlighted, returns another sentence with the same usage of the high-lighted part.

Given a book, rate the complexity of its text by either sampling the paragraphs, or scan the complete text, paragraph by paragraph.