"So as" should be followed by to + verb. It expresses the ultimate purpose of some action, usually indirectly or in potential terms.
I purchased a ladder, so as to be able to reach the highest shelves.
(Note the indirect relationship: Buying a ladder does not directly let one reach higher. First, one must actually take the ladder home, put it on the ground, and climb onto it.)

"So as to" is somewhat weird. It's not actually wrong, but I don't think GMAC would include it in an incorrect answer.
(This is not the same as so + (adjective) + as to + (verb), which is a common construction: Some of these feats are so difficult as to be nearly impossible even for the world's most accomplished athletes.

"So that" is followed by a complete sentence, expressing the purpose of something. Its meaning is a lot like that of "so as to".
Jimmy bought a ladder so that he could reach the top shelves.

Official Answer:
Idiom; Logical predication
The sentence describes the Ptoiemys' objective in founding a library as a location where Greek literature could be gathered together and systematized. The correct version of the sentence makes this locational importance clear.
A. The connector so as is imprecise and unidiomatic. The correct expression would be so that.
B. Correct. A library is a location, and the phrase in which is consistent with this meaning.
C. The additive conjunction and does not accurately describe the relationship between the library and the gathering and systematizing of literature.
D. Whereby indicates that the library is a means of gathering and systematizing, instead of a place where this happens.
E. By which indicates that the library is an agent of gathering and systematizing, which makes no sense.
The correct answer is B.

being现在时态没必要

B选项值得仔细想想直接表达和用抽象名词+后面解释表转折二者的区别

those 指代costs
瞎了

E选项原来是因为和C比没必要而被排除，以为是因为那个for 。。。

政府目标：增加储蓄，然而人们只是把另外账户的钱转过来，储蓄总量没变
题目没看清，政府的目的！！！

have yet to 尚未，还没有

B項“tied to the prime ”這是什麽結構意思？

由于前提和结论讨论的事件不同，且结论是果，所以本题为因果推理；加强问法削弱取非

因果推理，
由于本题问的是加强，所以答案选项需在“削弱取非”后选

Area of brass square/ area of wooden strip = 25 /39
lets say length of the wooden plaque= l and length of the square brass = x
then
x^2 / (l^2 - x^2) = 25/39
=>39x^2 = 25l^2 - 25x^2
=>64x^2 = 25l^2
=>8x = 5l
Width of wooden strip should be l-x
=>x = 5l/8
so l -x = l = 5l/8 = 3l/8

Now 3l/8 could be any value depending on the value of l

even though it is the buyers 看成上一句的分句了。。。

难题。。。
ABE都可以排除，因为 flow out from...to..其中out显得多余了
C感觉没有语法错误，但是读起来就是很不爽，Google了一下感觉解释 也不太有说服力，但是D确实读起来要顺很多
附官方解释：
C. Japan's farm households are still nearly 5 million is confusingly phrased. As worded, it seems to indicate that there are 5 million people on farms in Japan rather than that the number of farm households in Japan is 5 million. The intended meaning would be better conveyed if it said there are still nearly 5 million farm households in Japan.

至少有一名的反向是一名都没有，用减法。10个选3个，C3 10。一名都没有相当于3名都是初级，则是C3 6。然后C3 10-C3 6

算比值

90 90 45 135

by the next larger integer. 比下个整数大1

看不懂题目……文字题是硬伤啊

存的总数是每个月没存的三倍，不是存的总是是没存总数的三倍！看清楚题目！