這是一個在四級作文裏麵用來闡述觀點的經典句型，用詞也很出色。
It is universally acknowledged that trees are indispensable to us. 全世界都知道樹木對我們是不可或缺的。
It is…that 句子…構成強調句型（The Emphatic Pattern）
英語常用的強調結構是“It is/was 被強調部分（主語、賓語或狀語） who（that）…”。一般說來，被強調部分指人時，用who；指事物時，用that；在美國英語中指事物時常用which來代替that。
與之類似的常用句型還有：
It is conceivable that 句子（可想而知的）
It is obvious that 句子（明顯的）
It is apparent that 句子（顯然的）
It is conceivable that knowledge plays an important role in our life. 可想而知，知識在我們的一生中扮演一個重要的角色。
第二步：語法精講
1. 簡介
(1) 一般情況用It is (was)…that (who)…，指人時，用who；指物時，用that。 ※本※作※品※由※思※兔※網※提※供※線※上※閱※讀※
我們分別可以強調主語、賓語、表語、時間狀語和地點狀語等。如：
He read three books in the library yesterday.（正常句子）
It was he who read three books in the library yesterday.（強調主語）
It was three books that he read in the library yesterday.（強調賓語）
It was in the library that he read three books yesterday.（強調地點狀語）
(2) 強調狀語或定語時，隻用that，不用when、where，如：
It is at 5 o’clock that the train will arrive.
(3) 被強調的部分是主語時，注意句子的謂語動詞和被強調的主語保持一致。如：
It is he who is late.
It is they who were late.
(4) 一般疑問句的強調句為“Is (was) it that…?”；特殊疑問句為：“特殊疑問詞 is (was) it that…?”結構。如：
Was it ten years ago that his father died?（他的父親是十年前去世的嗎？）
When is it that you will set off?（你到底什麼時候出發？）
(5)“not…until…”句型的強調結構為“It is not until…that…”應注意把否定詞not轉移到until前麵。如：
I didn’t go home until the rain stopped.（直到雨停了我才回家）。
強調句為：It was not until the rain stopped that I went home.
I didn’t know the news until yesterday.（直到昨天我才知道那個消息）
強調句為：It was not until yesterday that I knew the news.
2. 四級必考套句學習
(1) It is the responsibility of to do sth.
【分析】注意，從形式上看該句子很像強調句型，而實際上並非如此，因為句中it是形式主語，動詞不定式作實際主語。
It is the responsibility of every citizen in our s