has it been=it has been
已经过了(多久了)
It has been many years since we last saw each other.
上次见面到现在已经好多年了
换成疑问句,颠倒主谓就成了
how many years has it been since we last saw each other?
上次见面到现在多少年了?
主谓颠倒举例 it is a dog.is it a dog?