It is句型的种类
（1）It is time (for sb.) to do sth. //It is (high) time that sb. did sth.(虚拟语气) 该是做某事的时候了。 例如：
It is high time that we tried our best.// It is time for us to try our best.
（2）It is + 形容词（+of / for sb.）+ to do sth.
（3）It is + 形容词 + that + sb. + (should) do sth.（虚拟语气）
能用于这个句型的形容词有strange、wonderful、natural、good、proper、right、wrong、well、fortunate、important、necessary、useless、likely、probable、impossible等。有时可省去should而直接用动词原形。如：
It is important that we should pay close attention to grain.
It is natural that he（should）say so.
（4）It is no use/ good + doing sth. 做某事无意义
It is no use trying again = It is of no use to try again.
（5）It is + 被强调部分 + that/who + …
Was it in the street that you met her?
Who was it that called him\" comrade”?
It was not until yesterday that I met my old friend.
It is in a small factory that my brother is going to work. 注意上述各句为强调句型的“考点”）
比较：It is a small factory where my brother is going to work.（定语从句）
（6）It is said/reported/announced/ (well) known … that… 据说/据报道…
（7）It is/was + 时间 + since … 从……已多久了。
It is/ has been three years since I met him in Beijing.
It was a long time since I (had) lived in that small mountain village with these farmers.
（8）It is + 时间 + before …
这个句型和上面句型中时间都是时间段，如long、years、months、weeks、five days、three hours、twenty minutes等。不过主句的时态多用一般将来时或一般过去时。
It will be several years before we meet again.
我们要过好几年才能再见面。
It was not long before they set out for the front.
不久他们就出发去了前线。
（9）It is /was/will be the first/second/ … time that …第几次做某事
It is the first time that I have been here.
It was the second time that he had seen the film.
（10）It is up to sb. to do sth … 应由某人做某事。
It is up to you to decide whether we start or not.
1. It was the third time _____ he had done this experiment.
A. since B. before C. which D that
2. ——What was the party like?
—— It’s years _____ I enjoyed myself so much.
A. after B. before C. when D. since
3. It has been two years _____ he ____ the army.
A. before; joins B. that; joins C. since; joined D. when; joined
4. It was about 600 years ago ____ the first clock with a face and an hour hand was made.
A. that B. until C. before D. when
5. It was with great joy _____ he received the news that his lost daughter had been found.
A. because B. which C. since D. that
6. It was the first time that the old woman _____ in this city.
A. has been B. came C. was D. had been
7. It is certain _____ he will go over his business to his son when he gets old
A. which B. that C. before D. since
8. It will be weeks ____ our headmaster comes back.
A. as B. since C. before D. until
9. It is these poisonous products ____ can cause the symptoms of the flu, such as headache and aching muscles.
A. who B. that C. how D. what
10. It ______ long before we _____ the result of the experiment.
A. will not be; will know B. is; will know
C. will not be; know D. is; know
1.D。It/ This/ That + be + the first (second…) time + that从句。该句型中that从句要求用完成时态。have been to“已经去过（某地，现在人已经不在哪儿）”。Have gone to“已经出发到（某地，尚在途中或刚到达）”。
在这一句型中，如果句中的be动词为一般现在时is，that从句中的谓语动词用现在完成时have(has) done sth.。如果主句中的be动词为一般过去时was，that从句中的谓语动词用过去完成时had done sth.,意为“这（那）是某人第几次做某事了”。例如：It is the second time that he has been in Japan.“这是他第二次去日本”。He told us it was the third time that he had visited the Great Wall of China.“他告诉我们那是他第三次游长城”。
2. D。此题考查句型：It + be + 一段时间 + since从句。译文：“聚会如何?”
“非常好。我已经好多年没有那么高兴了。”since从句中的enjoyed myself表示在过去曾经那么高兴过，但是没有那样高兴已经延续了多年”。
在这一句型中，主句中的be动词常用is或has been, since引导的从句中的谓语动词常用一般过去时。如果主句中的be动词为was, since从句中的谓语动词则用过去完成
时。注意：从句中的谓语动词如果为短暂性动词，应为肯定意“某人做某事已经有多长时间了”；如果从句中的谓语动词为延续性动词，则为否定意“某人已经有多长时间没做某事了”。又如：It is/has been three years since he left his village.“他离开村子已经有五年了”。It was six years since she had lived in this city.“那时他不住在这个城市已有三年了”。有时考查该句型中的谓语动词。
3. C。此题考查句型：It + be + 一段时间 + since从句。详见第2小题。
4. A。此题考查强调句型: It + be + 被强调部分 + that + 陈述句。
5. D。本句为强调句型: It + be + 被强调部分 + that+ 陈述句。
选择时要注意两点：用疑问语序；特殊疑问词充当say 的宾语，必须使用代
词what, what又是被强调部分。句中be动词的时态形式只可用is或was。陈述句部分的谓语动词如果是一般现在时态或将来时态，be动词用is；如果是过去的某一种时态，be动词用was。这一结构可以对句中的主语、宾语或状语加以强调，但是不能对句子的谓语进行强调。强调人时可以用who/whom代替that。强调其它成分只能用that。（特别注意：强调时间或地点时，不可以用when, where连接，只能用that）。其意义可以视情况而定。
6. D。详见第1小题。
7. B。本句为主语从句: It + be + adj. + that-clause。
8. C。此题考查句型：It + be + 一段时间 + before从句。before“（…之后）
才…”。译文：“要过好几个星期校长才会回来”。
在这一句型中，如果陈述过去所发生的事情，主句中的be动词常用was/wasn’t , 从句中的谓语动词常用一般过去时态，构成“It + was/wasn’t + 一段时间 + before sb did sth.”，意为“过了（没过）多久某人就干某事了”。如果陈述将来要发生的事情，主句中的be动词用will/won’t be, 从句中的谓语动词用一般过去时态，构成“It + will/won’t be + 一段时间 + before sb does sth.”，意为“要（不要）过多久某人就（才）会干某事”。例如：It was years before he returned.“过了好多年他才回来”。It won’t be two hours before we finish the job.“要不了两个小时我们就会完成这项工作”。
9. B。详见第5小题。
10. C。详见第8小题。
1．There are still many problems of environmental protection in recent years. One of the most serious problems is the serious pollution of air, water and soil. the polluted air does great harm to people’s health. The polluted water causes diseases and death. What is more, vegetation had been greatly reduced with the rapid growth of modern cities.
To protect the environment, governments of many countries have done a lot. Legislative steps have been introduced to control air pollution, to protect the forest and sea resources and to stop any environmental pollution. Therefore, governments are playing the most important role in the environmental protection today.
In my opinion, to protect environment, the government must take even more concrete measures. First, it should let people fully realize the importance of environmental protection through education. Second, much more efforts should be made to put the population planning policy into practice, because more people means more people means more pollution. Finally, those who destroy the environment intentionally should be severely punished. We should let them know that destroying environment means destroying mankind themselves.
2. Environmental problems are becoming more and more serious all over the world. With the development of industry and agriculture, cars make great noises and give off poisonous gas. Trees on the hills have been cut down, and waste water is being poured continuously into rivers. Furthermore, wherever we go today, we can find rubbish carelessly disposed. The whole ecological balance of the earth is changing. Massive destruction of environment has brought about negative effects and even poses a great threat to man's existence.
We must face the situation that exists and take actions to solve our environmental problems. For instance, new laws must be passed to place strict control over industrial pollution, the public must receive the education about the hazard of pollution and so on. We hope that all these measures will be effective and bring back a healthful environment.
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