文档介绍：加强（strengthen）
3. (24275-!-item-!-188;#058&000768)
The prairie vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters. Voles commonly live in large groups from late autumn through winter; from spring through early autumn, however, most voles live in far smaller groups. The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.
Which of the following, if true, provides the strongest support for the explanation offered?
(A) It is in the spring and early summer that prairie vole communities generally contain the highest proportion of young voles.
(B) Prairie vole populations vary dramatically in size from year to year.
(C) The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring.
(D) Winters in the prairie voles' habitat are often harsh, with temperatures that drop well below freezing.
(E) Snakes, a major predator of young prairie voles, are active only from spring through early autumn.
支持：原因，说明原因的确发生了的列子。
7. (24651-!-item-!-188;#058&001089)
As part of major renovations to Flowertown's Main Street train station, consultants to the train company proposed moving the station's entrance from its current valuable Main Street location to a low-rent adjoining side street and then leasing the high-rent entrance space to retail businesses. In that way, the train company could easily pay for those and all other proposed renovations without negative impact on its tight budget.
Which of the following, if true, would most strongly support the consultants' proposal?
(A) More train commuters are employed in businesses located on Main Street than in businesses located on the adjoining side street.
(B) A reliable survey of Flowertown's commuters showed that virtually none of them would use the train any less frequently if the station's entrance were