The kinds of hand and wrist injuries that result from extended use of a computer while maintaining an incorrect posture are common among school children in Harnville. Computers are important to the school curriculum there, so instead of reducing the amount their students use computers,teachers plan to bring about a sharp reduction in the number of these injuries by carefully monitoring their students' posture when using computers in the classroom.
Which of the following would it be most useful to know in order to assess the likelihood that the teachers' plan will be successful?
(A) Whether extended use of a computer while maintaining incorrect posture can cause injuries other than hand and wrist injuries
(B) Whether hand and wrist injuries not caused by computer use are common among school children in Harnville
(C) What proportion of schoolchildren in Harnville with hand and wrist injuries use computers extensively outside the classroom
(D) Whether changes in the curriculum could reduce the schools' dependence on computers
(E) What proportion of schoolchildren in Harnville already use correct posture while using a computer
虽然有些同学认为B 选项也能对最终children是否有injuries造成影响，但是本题探讨的是extended use of a computer对hand and wrist injuries的影响关系，所以injuries not caused by computer use就属于跳出探讨范围的错误选项了。其实GMAC官方出题对这一方面的考察很多，PREP 08中有一道学生经常搞不清楚的题也与此相似：
Early in the twentieth century, Lake Konfa became very polluted. Recently fish populations have recovered as release of industrial pollutants has declined and the lake’s waters have become cleaner. Fears are now being voiced that the planned construction of an oil pipeline across the lake’s bottom might revive pollution and cause the fish population to decline again. However, a technology for preventing leaks is being installed. Therefore, provided this technology is effective, those fears are groundless.
The argument depends on assuming which of the following?
(A) Apart from development related to the pipeline, there will be no new industrial development around the lake that will create renewed pollution in its waters.
(B) There is no reason to believe that the leak-preventing technology would be ineffective when installed in the pipeline in Lake Konfa.
(C) The bottom of the lake does not contain toxic remnants of earlier pollution that will be stirred into the water by pipeline construction.
(D) Damage to the lake’s fish populations would be the only harm that a leak of oil from the pipeline would cause.
(E) The species of fish that are present in Lake Konfa now are the same as those that were in the lake before it was affected by pollution.
该题探讨的是the planned construction of an oil pipeline对pollution的影响关系，因此A选项中其他new industrial development就属于跳出探讨范围的错误选项了（正确答案为C）。