UPDATED: DEC 2021
Answers the question:
Q: How long + has it been since + pronoun + verb?
A: It has been + time + since
- Must learn grammar.
- It's = It has
- Event in the Past + Present and Continuing = Present Perfect
EXAMPLES - short answer - best option.
How long has it been since John worked in Saudi Arabia?
- Since 2000.
- 21 years.
EXAMPLES - long answer
How long has it been since you were in Singapore?
- Not since 2000.
- It's been 21 years.