it is time that 的用法是怎样用的

it is time that +从句,从句要用虚拟语气；有两种方式：
从句用作一般过去时。
例：It is time that we went to bed.
我们该上床睡觉了。
从句用should+动词原形。
例：It is time that we should go to bed.
我们该睡觉了。