1. According to a study by the Carnegie Foundation for the Advancement of Teaching, companies in the United States are providing job training and general education for nearly eight million people, about 【equivalent】 to the enrollment of the nation's four-year colleges and universities.
(A) equivalent to the enrollment of
(B) the equivalent of those enrolled in
(C) equal to those who are enrolled in
(D) 【as many as】 the enrollment of
(E) 【as many as are enrolled in】
解析：【equivalent】1、作为形容词之后跟to，作为名词之后跟of。
2、A B C错在用equal to、equivalent of、equivalent to表示两者在某种性质点上的等价，用在此处会导致逻辑上的搭配不当。原句暗示的是人在数量上的一样多，因此，用as many as表示数量上的相等更加确切。
【as many as】as many as之前的复数people与其后的单数enrollment不具有可比性。
【as many as are enrolled in】主语省略，原句应是：people are enrolled in，但比较对象名词相同可以省略。
2.A migraine typically afflicts one side of the head, lasts for hours 【or】 days, and may recur as infrequently as once every other month or often, as daily.
(A) as infrequently as once every other month or often, as
(B) 【as infrequently as once every other month or as often as】
(C) infrequently, as often as once every other month, or often, like
(D) infrequently, like once every other month, or often, like
(E) infrequently, like once every other month, or as often as
解析：
【or】 两个同价比较的平行结构，中间用or连接，e.g.： or…and…as…as ，ACDE不满足平行结构对称要求。
1、CDE中like不能用作同阶比较，且举例要用such as而不用like
【as infrequently as once every other month or as often as】对称工整：
1、as infrequently as对应 as often as
2、once every other month对应daily
3.Inflation has made many Americans reevaluate their assumptions about the future 【;】 they still expect to live better than their parents have, but not so well as they once thought they could.
(A) they still expect to live better than their parents have
(B) they still expect to live better than their parents did
(C) they still expect to live better than their parents 【had】
(D) still expecting to live better than their parents had
(E) still expecting to live better than did their parents
解析：
【;】分号前后对应的是完整的句子，排除D E;对同一群体不同时间条件下的统一动作的比较：本句谓语动词是live而不是expect。
【had】had表示过去完成时没有根据。
4.The guiding principles of the tax plan released by the Treasury Department could have even a greater significance for the economy than the particulars of the plan
(A) even a greater significance for the economy than
(B) a significance that is even greater for the economy than
(C) even greater significance for the economy than have
(D) even greater significance for the economy than do
(E) a significance even greater for the economy than have
5.Once positioned in space, the Hubble Space Telescope will capture light from sources 【twenty times fainter】 compared to those that can be detected by ground-based instruments.
(A) compared to those that can be detected
(B) compared to those that can detect
(C) than that can be detected
(D) 【than those that can be detected】
(E) than those detecting
解析：
【twenty times fainter】
【than those that can be detected】
答案：1.E 2.B 3.B 4.D 5.D