Question

it is high time后接的从句是什么从句，详细解释一下

Answer 1

It is high time that...后跟虚拟语气，后跟动词的一般过去式，表示“是某人做。。。的时候了”或者“是某人不做。。。的时候了”
短语如下：
It is high time that 是时候...; 现在是时候了... ;
it is high time to 该做...了；
It is high time for action. 该采取行动了；
It is high time you made up your mind. 你该拿主意了；
例句如下：
（1）It is high time that we taught them that the data they gather will help the economyas well.
现在正是我们让他们知道他们收集的数据也会帮助经济的时候。
（2）It is high time everyone came to grips with the consequences of overusing theearth's resources, including the misuse of land in the pursuit of economic wealth.
然而，我们已过度使用了地球的资源，包括为了追求经济繁荣而滥用的土地，如今该是我们认真面对这个后果的时候了。

Answer 2

it is high time +句子（谓语动词是一般过去时）
例句：
it is ( high ) time she was here / she came .
-----用于讲话人对某事/某人不耐烦，表达的是：某事/某人应该早就- - - 。这不是“虚拟语气”。