It's 20 years since.It's 是is 还是has

It's 20 years since.It's 是is 还是has 翻译 It's five years since he smoked It has been 2 years since it's years since i It's four years since Mike ____ to Tibet.A.has been B.is com it's gone,这里的it‘s是it has 还是it is? It is five years since my father___?后面是用has been dead还是died? it is two years since I came here还是it has been two years sin It's about three years since they＿here.是填came还是have been? It's ten years since we last met in Beijing?句型中is能否用has been It's a long time since还是It has been a long time since It`s been a pleasure to talk to you.中 It`s 是It has 还是It is? it's nothing to do with me .其中的it's,是it is还是it has?这俩有区别么?