可以加动词原形，也可以加动词过去式。It's high time that意思是应立即做(某事)的时候了，早就到了做什么的时候了。It is(high)time that后面的从句，谓语动词要么用过去式或者用should+动词原形，但should不可省略，这是虚拟语气的用法。两者意思一样。

it's high time用法

1、It is (high) time that表示“是该做......的时候了。

后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。

2、It’s high/good time that+从句句式

这种句式常用it作形式主语，that从句为主语从句，句中常用一般过去时或“should+do”的虚拟语气结构。注意：其中should不可省略; time前不加定冠词the

结构：It’s (high/about/good)time that sb did/should do sth

3、还有一种结构就是it is high time+to do sth,不是虚拟语气，意思是到做......的时候了。

it's high time例句

I think it's high time that we stopped having fish and chips every Friday.

我觉得我们真的得改变每周五都吃炸鱼和薯条的习惯了。

All right, it's high time we did.

好的，现在该是送去的时候了。

It's high time he made up his mind.

他该拿主意了。

It's high time you left home for work.

你真该离家去上班了。

It's high time you were all in bed!

它们全都在各种借口下走掉了。