真正的英语语法高手请进吧

It's time…句型是中学英语里使用频率较高的句型，其意为“该是……的时候了”。用法灵活多变，也是大家以掌握的句型。现就其有关句式归纳如下：
⑴ It's time for + n.“该是（干）……的时候了。”例：
Boys and girl, It's time for class.
同学们，该上课了。
⑵ It's time + (for sb.) to do sth. .表示“该是（某人）干……的时候了。”例：
It's time for you to clean the classroom.
该是你打扫教室的时候了。
It's time to go to school.
该去上学了。
⑶ It's time + that clause 时，that可省略，time可由high,about修饰，从句中的谓语动词有两种形式，或者用动词的过去式(be用were)；或者用shoud + 动词原形（should不能省略)。此句型为虚拟语气句型，表示“现在某人该做某事了”。含有该事早该去做而未做，现在去做似乎都为时已晚的意思。例：
It's time （that）we went to bed.
我们该去睡觉了。
It's high time that the article were published.
发表这篇文章是适时的。
It's time you should do cleaning.
你该去打扫卫生了。
⑷ It's + the/序数词+ time +to do sth. 表示某人第几次做某事。例：
It is my first time to write letter in English.
这是我第一次用英语写信。
⑸ It's + the+序数词+ time+ that clause.也 表示某人第几次做某事。例：
It is my first time that I've even written letters.
这是我第一次用写信。
句型⑷ 句型 ⑸ 可以互换。

It is high/about time that 正是干……的时候了high/about 只是对time 强调

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。

It is time that the children went to bed.

It is high time that the children should go to bed.

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所以这个句型主要是用来强调的，就和if一样并不一定是虚拟语气的
但是当用虚拟语气的时候要加were一样的道理

你看到过 “it's time we left" 这个句子吗？因为我个人认为，应该是说”it's time we leave"
还有 should 是可以省的，在虚拟语气中，比如说suggest后面都可以
e.g. I suggest we (should) leave now.