三道语法携隐

luodanxuanUID：2462195

这三道我看了携隐的解释也不能理解，那个解释很模糊的，所以想请教NN们帮我分析下答案
*211. The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleolithic people has been established by carbon-14 dating, but what is much more difficult to determine are the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals.
(A)  has been established by carbon-14 dating, but what is much more difficult to determine are
(B)  has been established by carbon-14 dating, but what is much more difficult to determine is（B）
(C)  have been established by carbon-14 dating, but what is much more difficult to determine is
(D)  have been established by carbon-14 dating, but what is much more difficult to determine are
(E)   are established by carbon-14 dating, but that which is much more difficult to determine is

这题我选的A，为什么最后不是are是is？

*208. Teratomas are unusual forms of cancer because they are composed of tissues such as tooth and bone not normally found in the organ in which the tumor appears.
(A)  because they are composed of tissues such as tooth and bone
(B)  because they are composed of tissues like tooth and bone that are
(C)  because they are composed of tissues, like tooth and bone, tissues
(D)  in that their composition, tissues such as tooth and bone, is
(E)   in that they are composed of tissues such as tooth and bone, tissues（E）

为什么B不行？




*199. Because the Earth's crust is more solid there and thus better able to transmit shock waves, an earthquake of a given magnitude typically devastates an area 100 times greater in the eastern United States than it does in the West.
(A)  of a given magnitude typically devastates an area 100 times greater in the eastern United States than it does in the West
(B)   of a given magnitude will typically devastate 100 times the area if it occurs in the eastern United States instead of the West
(C)  will typically devastate 100 times the area in the eastern United States than one of comparable magnitude occurring in the West
(D)  in the eastern United States will typically devastate an area 100 times greater than will a quake of comparable magnitude occurring in the West（D）
(E)   that occurs in the eastern United States will typically devastate 100 times more area than if it occurred with comparable magnitude in the West

A不行吗？


[ 本帖最后由 luodanxuan 于 2008-9-22 17:34 编辑 ]

TyliayssUID：185761

211题:划线部分有what is more........这里都是is了为什么后面要用are呢.....?这个答案比较强词夺理;d:

208题:举例都是用的such as不用like

199题:用A的话文章的大意有点模糊绕不出来了.D句表达相对清晰一些,就是一个地区的情况跟另一个地区的情况的比较