从句谓语通常用过去式表示现在或将来，有时也用过去进行时或should+动词原形(较少见，且should不能省略)，其意为(早)该干某事了。如：
I think its time you went to bed. 我想你该睡觉了。
Its time we went [were going, should go]. 我们该走了。
【注】(1) time前有时有about和high修饰。如：
Its high time you bought a new car. 你该买辆新车了。
(2) 与其他的虚拟结构不同，该结构不能在该用was时而用were。如：
Its time I was in bed. 我该上床睡了。(不用were)