2 主语比较特殊形式
　　2.1 双重比较：(主语+状语 vs．主语+状语，一般需要用those，that等)
　　单纯主语
　　GWD3-30
　　Today's technology allows manufacturers to make small cars that are more fuel-efficient than those at any other time in production history.(不能用they)
　　37．GWD25-Q37.
　　Though the law will require emissions testing of all diesel vehicles, from tractor trailers to excursion buses, it will have no effect on sport utility vehicles, almost all of which are gasoline powered and therefore not subject to emissions-control standards as stringent as those for diesel-powered vehicles.
　　(as stringent as 修饰standards，后面的those也指代standards，可以改成：not subject to emissions-control standards as stringently as diesel-powered vehicles are，are必须补出来，否则可能表示跟standard进行比较 )
　　Paper production accounts for approximately 40 percent of the world's industrial use of wood, and the market for paper is growing faster than the market for all other major wood products.
　　114．(30583-!-item-!-188;#058&004275)s
　　A study on couples' retirement transitions found that women who took new jobs after retiring from their primary careers reported high marital satisfaction, more so than those who retired completely.
　　主语加谓语
　　According to public health officials, in 1998 Massachusetts became the first state in which more babies were born to women over the age of thirty than under it.
　　Four times as many Americans were killed as (those that ) would later be killed (比较双方省略，突出比较对象本身。)
　　Prep2-96．(29547-!-item-!-188;#058&004302)
　　There are hopeful signs that we are shifting away from our heavy reliance on fossil fuels：more than ten times as much energy is generated through wind power now as was the case (generated through wind power now than it was ) in 1990．(括号中的部分不对，因为用了it) (可以改成 as was generated in 1990)
　　Those small domestic mills will take more business from the big American steel mills than (those that) would have been taken by the foreign steel mills in the absense of quotas．(主动、被动比较)
　　Currently, researchers collect far more background information on patients than (that which) is strictly required for their trials.(省略that which)
　　GWD7-Q4:
　　Only seven people this century have been killed by the great white shark, the man-eater of the movies— fewer than have been killed by bee stings.
　　nearly eight million people，as many as are enrolled in the nation's four-year colleges and universities.(省略了those who)
　　Prep2-39．(26492-!-item-!-188;#058&003168)
　　As is the case with traditional pharmacies, prescriptions are the cornerstone of a successful on-line drugstore, since it is primarily prescriptions that attract the customers, who then also buy other health-related items.
　　A new genetically engineered papaya was produced not by profit-motivated seed companies, as was the case with most genetically modified crops previously approved for commercial use, but by university and United States Department of Agriculture researchers who allowed growers to use it free of charge.
　　2.2 整句比较
　　Possible/necessary/previously thought/会省略be动词，如果前面加了currently，medically等，be动词就不省略了
　　Prep1-45
　　Applying a new method for analyzing the chemistry of tooth enamel, scientists have examined molars of prehuman ancestors and determined that their diets were more varied than had been supposed．( than they had been supposed to be )
　　Prep1-152
　　Recent research indicates that two popular arthritis drugs may not be as safe as they were initially believed to be.
　　Prep1-43
　　A one-million-year-old skull bearing traits associated with both Homo erectus and Homo sapiens has been found in the Afar region of Eritrea, indicating that modern humans developed much earlier than previously thought．(than people previously thought they develop，or what)
　　77．(28689-!-item-!-188;#058&003708)
　　Scientists have found signs that moving water changed the chemical makeup of the surface of Mars in recent eras and have therefore concluded that the planet's crust harbors up to three times as much water as previously thought.
　　up to three times as much water as (that which have been )previously thought
　　GWD7-Q32:
　　A surge in new home sales and a drop in weekly unemployment claims suggest that the economy might not be as weak as (the economy) some analysts previously thought (to be).
　　22．(25727-!-item-!-188;#058&002127)
　　The company announced that its profits declined much less in the second quarter than analysts had expected and that its business would improve in the second half of the year.
　　at speeds much higher than (those that) are currently possible(状语比较，比较的是主语)
　　areas that exhibit as many of the critical features as (those that are) possible
　　3 主语比较错误形式(不能用they/it，要用those/that)
　　GWD3-Q30:
　　Today's technology allows manufacturers to make small cars more fuel-efficient now than at any time in their production history．( C )
　　A．small cars more fuel-efficient now than at any time in their
　　B．small cars that are more fuel-efficient than they were at any time in their 不能用they
　　C．small cars that are more fuel-efficient than those at any other time in
　　D．more fuel-efficient small cars than those at any other time in their
　　E．more fuel-efficient small cars now than at any time in
　　GWD1-Q16:
　　Soaring television costs accounted for more than half the spending in the presidential campaign of 1992, a greater proportion than (it was) in any previous election.(去掉it was。It指proportion，不对)
　　一下为别的比较:
　　34．GWD30-Q34：正确
　　Books in European libraries last longer than books in libraries in the United States because, although the climate in Europe is fairly humid, libraries there are not subjected to the extremes of temperature and humidity that damage collections in the United States．可以的，同一套extremes即damage了欧洲的，也damage了美国的。
　　以上对GMAT语法考试中的常见备考要点进行了较为详细的阐述，考生不妨以此为鉴，通过反复练习逐步掌握其在GAMT语法考试中的使用规律，从而在GMAT语法考试中发挥出更好的水平。