[求助]prep一道逻辑题。

trtwarrior

今天用模考软件做了一套题。。有一道逻辑题怎么也没弄明白。请各位大侠帮着理解理解吧。。
In Kravonia,the average salary for the jobs requiring a college degree has always been higher than the average salary for jobs that do not require a degree.Over the last few years, the number of Kravonians enrolled in college has been growing steadily. Therefore, the number of Kravonians entering the job market who have at least the qualification of a college degree will eventually be significantly higher than it has been over the last few years.  问题：下面哪个选项weaken了结论。
A）krovonians with more than one college degree earn little more, on average, than do Kravonians with only one degree.
B) The average number of years Kravonian college students remain enrolled before completing a degree has been increasing over the past several  years
C)Despite the increase in the number of Krovonians attending college, the percentage of the population attending college is lower in kravonian than in most other countries
D)In recent years, employers have been requiring college degrees for jobs that were previously performed successfully by Krovonians who did have college degrees.
E) For many years, employers in Krovonians have had difficulties finding enough college graduates to fill the high-paying jobs that were available.
答案是B啦。。虽然得出正选不难。。其它几个选项都太无关了。。可是仔细推敲。。觉得B也有问题啊。就算大学年限增加了。最终（eventually）进入就业市场的有学位的人数仍然会增加的啊。。这些人总归会毕业的吧。。逻辑题不是要注重答案的具体性的么。。还是我钻牛角尖了。。

reddragon

In Kravonia,the average salary for the jobs requiring a college degree has always been higher than the average salary for jobs that do not require a degree.Over the last few years, the number of Kravonians enrolled in college has been growing steadily. Therefore, the number of Kravonians entering the job market who have at least the qualification of a college degree will eventually be significantly higher than it has been over the last few years.  问题：下面哪个选项weaken了结论。
A）krovonians with more than one college degree earn little more, on average, than do Kravonians with only one degree.
B) The average number of years Kravonian college students remain enrolled before completing a degree has been increasing over the past several  years
C)Despite the increase in the number of Krovonians attending college, the percentage of the population attending college is lower in kravonian than in most other countries
D)In recent years, employers have been requiring college degrees for jobs that were previously performed successfully by Krovonians who did have college degrees.
E) For many years, employers in Krovonians have had difficulties finding enough college graduates to fill the high-paying jobs that were available.

citidandan

Therefore, the number of Kravonians entering the job market who have at least the qualification of a college degree will eventually be significantly higher than it has been over the last few years

我觉得是因为题目最后把题目的有效时间段限制在over the last few years，如果学校的年限增加到超过了over the last few years就可以weaken了

sunflower88

同问这题B如何削弱结论，不明白

captain_mas

the problem with this argument is that it takes the observation that "the number of Kravonians enrolled in college has been growing steadily", and takes that observation to mean that the number of graduates is going to increase in proportion.

choice (b) attacks this connection -- if students are taking longer to graduate from college, then the increased enrollment doesn't necessarily mean that there will be any more graduates! it's just a symptom of the fact that students are staying in school for longer.

for instance, if students take 4 years to graduate from college and college graduates 1000 students per year, then (not counting dropouts) that college's enrollment will be approximately 4000 students.
if students begin to take five years to graduate from college, then that same college will begin to have an enrollment of 5000 students -- even if it graduates the same number (1000) of students per year.
也就是说由于在学校呆的时间长了，使得在校人数增加了，但是每年毕业的人数没有增加