when the water temperature is abnormally high-the phenomenon called EI Niño- the chances of cold winter weather over North America increase. The opposite situation, when surface temperatures are well below normal-La Nina-is far less common.

D，with transpiration from soil and from plants to return approximately 21 inches to the atmosphere是一个独立主格结构。我们至少需要将其中的不定式短语to return approximately 21 inches to the atmosphere改为分词短语returning approximately 21 inches to the atmosphere，这点考查了不定式和ing的区别。用之于本题，主句the rest of the 9 inches contributes to the flow of streams and rivers和return句分属两个不同的方面（水的两个去处），所以主句的发生不会引起从句状态的改变，应选择非不定式的选项。

ling to sth | cling on to sth
to be unwilling to get rid of sth, or stop doing sth 不愿放弃；坚持

But clinging to this ideology also prevented these women from even attempting to gain true political power because it implied a moral purity that precluded participation in the messy world of partisan politics.

C，Scientists are successful in mining heat to produce energy on a commercial scale, enough for generating electricity efficiently and for heating factories and homes.
逗号后面形容词作状语，就近修饰produce energy这个动作
形容词作状语：Happy about his birthday, Joe made a cake for his family.
形容词作同位语：People, old and young, took to the streets to watch the parade.

C，Eutrinos are harmless elementary particles produced in nuclear reactions and which interact very weakly with matter.
连词+分词构成定语或状语，When studying GMAT, I feel hard.
which是代词不是连词，不能which+分词构成定语或状语。如果将C的第一个定语视为that/which的省略，应该是particles (which) ARE produced in nuclear reactions, 不能省略谓语be动词。所以C的第一个分词定语与第二个which引导的定语不能平行。

这篇文章单词好难啊，完全看不懂。

分大于0小于0的情况

(3) intention of doing sth. / intention to do sth. GMAT中通常不用intention to do sth.而只用intention of doing sth.
(4) ensure的固定搭配：
ensure + n.
ensure + that (后面直接跟陈述语气，不跟should be)

(1) intend的固定搭配： intend的动作发出者必须是生物。
intend somebody/something to do sth.
intend to do/doing sth. （后面跟to do和ing都可以）
intend that
be intended to do sth.：被用来做某事
be intended for somebody/something：表示书、电影、药品等专为…而设计或制造。
(2) intent的固定搭配：
noun. with intent (to do sth) 注意intent前没有the
intent of doing
adj. be intent on/upon (doing) sth： to be determined to do something or achieve something
intent on/upon 专注于
Intent upon her work, she didn't notice the cold.

x^2的隐含条件是>0!所以x>0!

疑惑自己为什么会错呢。这里x和n都是未知量。t也是。

原来pronounce是定语从句里的动词。。。我以为是work的定语。。。

A Because sloth is the object of a preposition and not the subject of the sentence, there is no reasonable antecedent for the pronoun it; in this construction, the subject of made is fossils, but it makes no sense to say that the fossils made it the earliest known mammal.
dated与found都是过去分词，共同修饰fossils，and前面不需要逗号；fossils使得sloth成为earliest known mammal逻辑意思不对，应该是年份鉴定的结果使之成为earliest known mammal；it指代不清楚，代词难以指到介词的宾语

关于monkfish, fish的单复数识别：
if "fish" is singular, it must be used WITH AN ARTICLE ("a", "the", etc.)
i saw a fish swimming beneath me --> singular (1 fish)
i saw fish swimming beneath me --> plural (multiple fish)

and 和consequently是什么词性
？ 可以一起用吗？

知道速度后，不需要知道起始时间。

两个的值都是唯一确定的

看错了！！！！

② k is divisible by exactly four different prime numbers.
是说k可以被4个不同的质数整除，并不是只有四个质数（就算是这样也不行：2,2,3,3,5,5,7,7）.
可被四个不同的质数整除：2,3,5,7,2（比如由这5个数相乘）