D that不能代复数speeds

E 省略了speeds ,at speeds much higher than currently possible speeds are. 在GMAT考试中，be动词可省可不省，但在这种现在与未来的比较当中，be动词最好不省。are提前是由于省略引起的倒装。

A but后不是that从句，语not that从句不平行

题目中包含一个假设：如果有trading goods，就一定会被发现。b项刚好强调了这个假设。c项中的the first比较无关，而且as much as possible仍然包含被损坏的可能。

（1）当2是n的一个质因子的时候，2n的different prime numbers和n的相等，因为2这个质因子在2n中重复了两次。
eg. n=2*3*5*7; 2n=2*2*3*5*7
当2不是n的一个质因子的时候，2n的different prime numbers比n多一个
eg. n=3*5*7; 2n=2*3*5*7
（2）n与n方个数个数应当相等
eg. n=2*3*5*7; n方=2*2*3*3*5*5*7*7

threaten the plan: (1) new modern buildings (2) lower tax
(A) Although long-term leases may adversely influence the plan in short term, some companies still will move to downtown provided that the loss of the default can be compensated by the gains from the move, such as lower tax.
(B) Irr: it doesn't matter.
(C) Definitely correct. Directly weaken the effect of one of the policies
(D) Irr: it doesn't matter. don't add asm by yourself.
(E) Irr cmpr: irrelevant comparison

No motifs appear in the Sepphoris mosaics that do not also appear in the mosaics of some other Roman city. 这句话没理解
翻译为：没在在罗马其他城市马赛克中出现的图案，也没在S的马赛克当中出现

(A) NTArg：the argument ask us to explain the discrepancy between Geckos population in rural and urban areas.
(B) NTArg: still, the information cannot prove the differences b/t Geckos ppl in rural and urban areas.
(C) IRR: irrlevant information.
(E) IRR: no matter whether the way geckos reproduce can influence the ppl or not, the information cannot explain the difference of geckos ppl in r and ur area. (btw, the stems do not offer any information about reproduction.)

我知道whereas 要求前后各个部分平行；但while没有这种要求吗？

这是因果推理把？

但 Presuming的逻辑主语是谁

比较ABC，当中whether, xxxx, yyyy， 这个xxx结构暂时不看
所以三个结构式
A.and whether those traces can
B.and whether can those traces
C.and whether those traces

B的结构错误，verb在subject前面，没有必要倒桩

则AC的区别就是是否应该存在这个can. 所以看前半句whether biological life forms ever emerged on Mars
动词是emerged，所以这里应该用exist，而不是can，这里不是情态动词平行

错选了D，后来明白过来 were studied 如果没有 if 搭配就变成了 “过去发生的”，namely已经知道了结果的事实，所以 D 语义逻辑就乱了。

B的话要是人就好了。。。

老师想请教您：为何中间不可以比较的是 不同的机构呢？总感觉那样子读起来很顺。。。

http://www.beatthegmat.com/according-to-a-1996-survey-by-the-national-association-t272968.html

B 选项中them应该是是指stars

看到这样的图，自动脑补为立体几何。。。
是不是如果是立体几何，题目都会特别说明？

不确定：
1. 因果推理：CQ1干扰因素
2. 枚举推理：CQ1样本代表性问题

不应该是CQ3 方案副作用问题吗