What is the formula of Present Perfect Continuous?

Related questions

1. What is Rule of future perfect tense?
2. What is future perfect continuous tense?
3. What are the examples of future perfect continuous tense?
4. What is past continuous tense with examples?
5. What effect does Active Voice have?
6. What is the future continuous?
7. Why there is no passive voice of future continuous?
8. How do you change a sentence into present continuous?
9. What is continuous tense with examples?
10. Will the future passive form?

Tags

1. #actions
2. #often
3. #continuous
4. #continuing
5. #formula
6. #began
7. #words
8. #tense
9. #still
10. #since
11. #present
12. #participle
13. #perfect