(2) It is + -\-\- + since S +持续性谓语动词(表否定) 例:It is three years since she lived here. 她已三年不住这儿了。 (3) It is / has been + -\-\- + since S + 瞬间谓语动词(表肯定) 例:It is years since I stopped smoking).我戒烟已经数年了。 十一. more...