句型是帮助大家理解课文的一个基础能力，外研版高一英语Unit4重点句型讲大家都掌握了吗?还不了解的同学赶紧来看看吧!!

It's been six years since we last saw each other, you know.     你要知道，我们已经6年没有见面了。

· 基本用法

句中you know 为插入语。 since引导的是时间状语从句，在这里是一个固定句型，即It has been +时间段

+ since + 一般过去时态。这个句型也可以表示成：It is +时间段 + since + 一般过去时态。 · 知识拓展

It is ... 句型总结如下：

1. It is (has been) + 一段时间 + since...

It is (has been) three years since he joined the army.、   他参军已经三年了。

It is (has been) ten years since Tom came to China.   汤姆来中国已经十年了。

It is (has been) two months since he worked here.   他两个月前在这儿工作。

2. It is(was, will be, not )+ 一段时间 + before...   It was a long time before he came back.    过了很久他才回来。

It will be soon before he comes back.   很快他就会回来了。

3. It is (was) + 时间点 + when...   It was midnight when he came back.   他半夜回来的。

And this is the first time I've visited your hometown.     这是我第一次到你的家乡来参观。

· 基本用法

句型结构“This + is + the + 序数词 + time + that 从句”中的time前面有序数词来修饰，后面的从句一般   要用完成时。如：

This is the second time that he has been to Beijing.   这是他第二次取北京。 · 知识拓展

It's time that....  该...时候了   It's high time that....   该...时候了   It's time that you went to bed.   = It's time for you to go to bed.    到了你上床睡觉的时候了。

It’s time that...... 句型中一般要用虚拟语气，从句谓语动词通常用过去式的形式，有时可用“should+ 动词

原形”的形式，should通常不能省略。