It is … since a) Past indefinite
b) Present perfect (non-continuous or continuous)
e.g. a) It is two hours since I saw them last.
b) It is two hours since she has been in the room.
A.1. It is ten months since… 2. It is over a year since … 3. It is ages since… 4. It is eight hours since … 5. It is twenty minutes since … 6. You have changed a lot. It is five years since .. 7. How time flies! It … since we have been living in this new district. 8. It … since she … in the hospital. She is taking treatment and is slowly getting better.