since后的从句谓语动词是延续性的,从动作结束算起.是非延续性动词从动作开始算起.这些是固定的.如 It is 2 years since he came here .他来这两年了.（came非延续）
It is 2 years since he lived here.他不住这两年了.(lived延续)
since后的从句谓语动词是延续性的,从动作结束算起.是非延续性动词从动作开始算起.这些是固定的.如 It is 2 years since he came here .他来这两年了.（came非延续）
It is 2 years since he lived here.他不住这两年了.(lived延续)