在GMAT語法題中，it與which不能指代前面整件事或整句話的意思，因為it與which也是代詞，所以當我們看到劃線部分出現了it或which的時候一定要注意是否有語法錯誤，it與which是GMAT語法考題中的高頻考點。
下面的這道題我們講的是it
1. More than five thousand years ago, Chinese scholars accurately described the flow of blood as a continuous circle controlled by the heart, but it went unnoticed in the West.
(A) but it went
(B) but it was
(C) although it was
(D) but the discovery went
(E) although the discovery was
答案：D
解析：五千年前中國學者精確地描述血液流動是被心臟控制的迴圈系統，但是這個()並沒有被西方所發現。這時候劃線部分出現了it，根據我們的判斷，在無法用單複數區分的'情況下，it優先指代主語，如果不指代主語就指代賓語。賓語是“血液流動”，如果it指代賓語，代入原文就變成了“血液流動並沒有被西方發現”，顯然西方的科技沒有落後到如此地步，it指代賓語是不正確的。It應該指代前面整句話，就是的血液流動是被心臟控制的迴圈系統這個現象。所以選D。由此，我們還可以得出一個結論，就是當代詞指代不清楚的時候，應該用一個概括性的抽象名詞來指代。
下面的這道題我們講的是which
2. The modernization program for the steel mill will cost approximately 51 million dollars, which it is hoped can be completed in the late 1980’s.
(A) The modernization program for the steel mill will cost approximately 51 million dollars, which it is hoped can be completed in the late 1980’s.
(B) The modernization program for the steel mill, hopefully completed in the late 1980’s, will cost approximately 51 million dollars.
(C) Modernizing the steel mill, hopefully to be completed in the late 1980’s, will cost approximately 51 million dollars.
(D) The program for modernizing the steel mill, which can, it is hoped, be completed in the late 1980’s and cost approximately 51 million dollars.
(E) Modernizing the steel mill, a program that can, it is hoped, be completed in the late 1980’s, will cost approximately 51 million dollars.
答案:E
解析：鋼廠現代化這件事花了51 million dollars，()有希望在1980年代被完成。A選項it is hoped插入語出現，前後應該各打逗號，且情態動詞出現，答案一定出現can。但是which不能指代整件事或整句話的意思，所以A錯。B和C選項hopefully是口語化表達，情態動can被省略掉了，所以都錯。D選項出現了代詞which，which不能指代整件事或整句話的意思，只能就近指代前面的名詞，在選項中which修飾的是steel mill，很明顯是錯的，因為()中說的是鋼廠現代化這件事花了51 million dollars這件事。所以，E選項正確。由此題，我們除了可以得出當代詞指代不清楚的時候，應該用一個概括性的抽象名詞來指代這個結論以外，還可以知道動名詞作主語時，謂語動詞應該為單數。
