请帮我选择并解释：It's nine O'clock and it's time you

问题补充：

请帮我选择并解释：Its nine Oclock and its time you

答案：

A 虚拟语气,后面句子用过去式.

======以下答案可供参考======

供参考答案1:

A,表虚拟语气，本应当