啥解释。。农民？seriously..wtf?

（1）xy同号 单独NS
（2）NS
(1) + (2) x，y都是正数 因为负数加上另一个负数不可能>0
所以x是正数，> 0, sufficient

如果需要分情况讨论的两种情况都是一个结果，那么就可以确定
（不要看到分情况讨论就觉得insufficient

(1) vk > 0
V and K can be either positive or negative, ranging from 1 to infinity on both side of number line.
(insufficient)

(2) v - k = 6
There are many possible combination with the given equation to determine one possible answer.
(insufficient)

Combining both : let v and k are positive integers
7-1 = 6, 8-2 = 6, ......... there are many possible combinations as the case with negative integers.
(insufficient)

(n + 4) - (n + 2) - n = -n - 2
已知n 是正奇数
-n必是负奇数
奇数和偶数的合是奇数
所以说是负奇数

DS 要时刻提醒自己 看清楚题目问的是什么 有时候不需要算出具体数值

PRS = QPR + PQR
所以只要知道QPR的角度即可求处PRS 比PQR 大多少
看清楚指的是什么角

PRS = QPR + PQR
所以只要知道QPR的角度即可求处PRS 比PQR 大多少
看清楚指的是什么角

DE本质前后没有强烈的因果关系

这答案怎么看都不对啊，D选项除了油漆其他的环境影响都不大，那就是油漆被环境影响的大喽。那这不是和题干是反的么

so...as to...与so...that...表达的意思一样，均为“太…以至于…”，一种因果关系。他们的区别在于，so...as to...用于主语和to后面的动作的发出者一致时，而so...that...中，主语与that之后的主语不需要一致。

但“经济变化是缓慢的”这件事导致的结果直接是“经济变化 是 难以辨别的”，而不是 “可以是”。也不是“没有能力被辨别”。

research在本选项中是及物动词，身后直接加宾语即可，不用再加介词短语（只有不及物动词才需要加介词短语来构成及物动词短语）。
while是连词，身后应该加完整的句子（表伴随状语时可以加分词短语），不能只加介词短语。

If these doctors drank more coffee, their likelihood of having coronary disease was greater.
可能性并非拥有的，而是客观存在的，所以是ing

解释的不对，不要看
attribute to和result重复

proposed：计划的，提议的。
current one与proposed speed limit对应

为什么study不能explain why 呢...？

解释都好生硬啊

Bi, can you stop justifying your ignorance?
According to the context , we can hardly assume the very intention of human being is to encounter more prey, nor should we justify the usage of "HAD done" .
In case of any refutation, here is the origin.
The research, which was published in the Feb. 9 issue of the journal Science, has implications both for the modern-day debate over reintroduction programs and for a historical debate over what happened 10,000 to 50,000 years ago, when one particular predator, humans, expanded its territory and encountered large numbers of native prey. Some experts think that a ''blitzkrieg'' of killing by advancing humans contributed to the extinctions of many large animals in that era.

See, It's an article from NY Times. what I wanna say is stop offering your misguidance and misinterpretation!

由并列连词and连接的两者平行的现象。实际上，这是一个省略和倒装的现象，还原后则有：
Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and Discussion of greenhouse effects has usually focused on what extent Earth would grow to.
划线部分均为省略内容。介词to倒装在了what extent身前。

needs和wants都是名词。。。我说做题的时候哪哪儿都不对