突然想到有必要說說這個強調結構了，強調結構在英語中的目的就是人如其名就是為了強調什麼。
它的基本結構就是 It is(時態可以變) xxxxxx that (who) ，你想強調句子中的哪個結構，就把哪個結構放到xxxxxx中去。要注意如果是人，需要用who，如果不是人其餘一律用that，沒有其他。
I want to have a square meal today.
如果我想強調主語我，那麼可以寫成：
It's I who want to have a square meal.
如果我想強調狀語今天，那麼可以寫成：
It's today that I want to have a square meal.
我們需要注意的是：
1）強調結構沒有任何語法功能，也就是如果你刪除上面例句的強調結構，句子依然是完整的，但是
it's said that I want to have a square meal.
這裡的it's ..that 是it做形式主語，並不是強調結構，怎麼區分呢？ 如果你把It's...that刪除，句子就不完整了。
2）強調結構是比較囉嗦的表達
在GMAT當中，從來不會強調什麼，不喜歡強調什麼。也就是我們常說的倒裝結構在GMAT中從來不是因為強調什麼而出現，而是因為避免頭重腳輕而出現。
同理 強調結構本身就是強調，所以GMAT中其實並不喜歡強調結構，因為它出現沒有理由，再這種標準的客觀的語言中，強調什麼就加入了感情色彩，不複合GMAT客觀的要求。
所以當你遇到強調結構的選項時候，不優選。
3）但是當遇到until...的時候，一切都變了....
首先我們來說說until的意思：
until 既可以做連詞也可以做介詞，也就是截可以接名詞，也可以接句子。我們來區分until vs not until...
I work very hard until the day before the exam. （我學習很努力一直努力到考試前一天：也就是考試前一天開始就放鬆自己了不努力了，之前都一直很努力）
I do not work very hard until the day before the exam. （我學習不努力直到考試前一天：這就是說我直到考試前一天才開始努力學習，之前從不努力學習。）
同時這句話也等於
not until the day before the exam I work very hard.
那麼再GMAT當中，我們強調結構非常愛和這個表達一起連用，也就是會變成： It's not until.that...
所以剛才的第二句，在GMAT當中會寫成：
It's not until the day before the exam that I work very hard.
但是意思沒有變化，仍然是：直到考試前一天，我才開始努力學習。
在GMAT中，強調結構被選的的情況主要是：
1）在使用 it's not until ..that 這個結構時
2）萬能的平行，任何不好的形式都可以因為平行存在而合理，比如平行二個強調結構或者其他的囉嗦的表達。
好的為了避免紙上談兵，還是趕緊來看一些真題吧：
It was only after Katharine Graham became publisher of The Washington Post in 1963 that it moved into the first rank of American newspapers, and it was under her command that the paper won high praise for its unrelenting reporting of the Watergate scandal.
It was only after Katharine Graham became publisher of The Washington Post in 1963 that it moved into the first rank of American newspapers, and it was under her command that the paper won high praise 二個強調結構平行
It was only after Katharine Graham's becoming publisher of The Washington Post in 1963 that it moved into the first rank of American newspapers, and under her command it had won high praise
Katharine Graham became publisher of The Washington Post in 1963, and only after that did it move into the first rank of American newspapers, having won high praise under her command
Moving into the first rank of American newspapers only after Katharine Graham became its publisher in 1963, The Washington Post, winning high praise under her command
Moving into the first rank of American newspapers only after Katharine Graham's becoming its publisher in 1963, The Washington Post won high praise under her command
Until 1868 and Disraeli, Great Britain had no prime ministers not coming from a landed family.
Until 1868 and Disraeli, Great Britain had no prime ministers not coming
Until 1868 and Disraeli, Great Britain had had no prime ministers who have not come
Until Disraeli in 1868, there were no prime ministers in Great Britain who have not come
It was not until 1868 that Great Britain had a prime minister— Disraeli—who did not come
It was only in 1868 and Disraeli that Great Britain had one of its prime ministers not coming
Although various eighteenth- and nineteenth-century American poets had professed an interest in Native American poetry and had pretended to imitate Native American forms in their own works, until almost 1900, scholars and critics did not begin seriously to studytraditional Native American poetry in native languages.
until almost 1900, scholars and critics did not begin seriously to stud
until almost 1900 scholars and critics had not begun seriously studying
not until almost 1900 were scholars and critics to begin seriously to study
it was not almost until 1900 when scholars and critics began to seriously study
it was not until almost 1900 that scholars and critics seriously began studying