It be…句型总结辨析

It句型全景复习

参考：Before作为连词的用法

      在平时学习过程中，经常遇到

It is / was…that / when / before / since…

It is / was the first / second / third…time that...等类似的句型，考生往往因分不清这些句型的用法而做错题。现将这些句型归纳如下，以便对比掌握。

1. It is / was…that…包括两种句型：

   (1) It is / was…that（引导主语从句）

1. It is clear that what he said is true.很明显他的话是对的。
2. It is well known that people all over the world are paying more and more attention to protecting our environment.
3. It is very important that we make every effort to make preparations for the coming examinations.

(2) It is / was----that / who（强调句型）

        这个句型可以强调除谓语之外的任何句子成分，被强调部分是人时，还可以用who代替that引导从句。

       强调句型与主语从句的辨别方法是：

       把“It is/was ......that”去掉后，如果句子的意思及语法结构仍然成立的话，就是强调句型。

   1. It was in 1998 when he was in middle school that he was nearly drowned. 他在1998年还在上中学时，他差一点被淹死。

   句1去掉“It was ......that”后就是：In 1998 when he was in middle school he was nearly drowned. 所以上句是强调句型。

   2. It was smoking that took his life away. 是吸烟送了他的命。

   句2去掉“It was ......that”后就是：Smoking took his life away. 所以是强调句型。

2. It is / was+时间点+when从句

      这种从句有两种情况：

(1) when为连词，引导时间状语从句，意为“当……的时候已是……时间了”。

It was four o'clock in the early morning when her husband came back.当她丈夫回来的时候已经是早晨4点了。

(2) when为关系副词，引导定语从句，意为“……是……时候”。不过这个句型容易和强调句型混淆。试区别：

<1> It was 1998 when he went abroad.（定语从句）他是在1998年去国外的。

<2> It was in 1998 that he went abroad.（强调句型）他是在1998年去国外的。

      句<1>中的“1998”是句中It was的表语，“when he went abroad”作“1998”的定语，而句<2>中“in 1998”是被强调句型所强调的状语部分，它的原句为：He went abroad in 1998 .

3. It”s (high) time+(that)从句

       注意从句的谓语动词形式用“一般过去时或should+动词原形”，意为“是该干……的时候了”。

• It's high time that we started / should start .我们该出发了。
• It's high time that  you should make every effort to prepare for the coming examinations.

4. (1) It is the first / second / third…time+that从句（从句用现在完成时）

    (2) It was the first / second / third…time+that从句（从句用过去完成时）

      意为“某人第……次干……”。

• It is the second time that I have been to Guangzhou.这是我第二次来广州。
• It was the third time that he had phoned me.这是他第三次给我打电话。

5. 到现在为止）干……有多长时间了。

   (1) It is/ has been+时间段+since从句（从句用一般过去时）。“（到现在为止）干……有多长时间了”。

    (2) It was+时间段+since从句（从句用过去完成时）。

• It is / has been six years since I came to this school to teach English. 我来这学校教英语已有六年了。
• It was six years since he had begun to learn English.他学了六年英语了。

     注意：如果从句中谓语动词是非延续性动词，表示“从该动作开始的那时刻起，有多长时间了”；从句中的动词是延续性动词或表示状态的动词，则该从句表示“从这个动作或状态的结束时算起，有多长时间了”；如：

— What was the party like?

─ Wonderful. It's years ___ I enjoyed myself so much.

  A. after   B. before    C. when   D. since

     正确选项为D。意为：“你觉得这次聚会怎么样？” “棒极了，我好多年都没有这么痛痛快快地玩了。”这里的

It's years since I enjoyed myself so much = I haven't enjoyed myself so much for years. 为什么 “enjoy” 的意义在这里变成了否定的呢？

    这是因为enjoy是持续性动词。当持续性动词用在since从句中时，其意义不同于非持续性动词。

• It is / has been two years since we began to use this machine.（began为非延续性动词）我们使用这台机器已有二年了。
• It is five days since he was ill.（was为延续性动词）他已康复五天了。 
• It is a week since he was in hospital他出院已有一星期了。

    通过以上例句可得出如下结论：

      在“It is + 时间 + since-从句” 的结构中，它表示从过去某一时刻起到现在（说话时刻）为止的一段持续时间的总和，从句中通常都用一般过去时，但无论用持续性还是非持续性动词都表示动作或状态的完成，时间的起点应该是在动作或状态完成的那一刻开始算起。例如：

1） It is six years since I joined the Party. 我入党已经有六年了。

2） It is six years since I was in Beijing. 我不在（离开）北京已经有六年了。

     在句2）中，无论在since从句前加ever还是在从句中用have been都无法表达“我已经在北京呆了六年”的意思。又如:

3）It is about five years since my father (has) smoked. 我父亲不吸烟已经约五年了。

(= It is about five years since my father gave up smoking.)

      所以， 前面“It’s years since I enjoyed myself so much.” 应译为“我好多年都没有这么痛痛快快地玩了。”这样才与上下文逻辑上一致。

6. (1) It was (not) / should (not) be+时间段+before从句（一般过去时）

 意为“（没）过多久就……

    (2)It is (not) / will (not) be+时间段+before从句（一般现在时）意为“要过了（一段时间）才……”

      It was not long before he worked out the problem . 没过多久他便解出了这道题。

• It will be two hours before he finishes his homework.还要两个小时才能完成作业。
• 参考：Before作为连词的用法