equip to face obstacle是过去，但appear是从现在的角度讲，故不用过去式

请问这里可以把破折号省略么，后面的句子加that直接做同位语从句。

C.的概念其實就是增加翻桌率

感觉c也可以啊，都是说明两个公司的不同点啊，因为r公司员工没有g公司员工更可能得这种病，所以不需要这么谨慎去体检之类的。

请老师分析一下A选项错在哪里，多谢~

能否再解释下，为何此处the energy一定是指the energy produced in France? 这个逻辑是基于什么？

[ref: beatthegmat]
A: THE MORE the city air would become INCREASINGLY
D: THE MORE the city air became INCREASINGLY
Here, the more and increasingly are redundant.
Eliminate A and D.

date的约束力比较弱，主被动都比较弱，因为无论date/ be date也好，宾补该是怎么样就是怎么样

如果这句话用equally来说的话应该怎么说呢～

如果考试的时候遇到这种题该怎么办呀，完全把leave behind 想反了

是不是方案推理呢

which is tested two ways on the GMAT.
1. nonessential clause set off by a comma.
2. replacement of "that." "which" needs a preposition because the use of "which" in this case. Which is a relative pronoun and must have a referent. "An era" is the referent.

補充Ｃ選項

OG解答提到but省略主語，但although省略是有問題的。
句子如果是符合省略要求，還原回來為Sunspots appear on the surface of the Sun as dark spots although [Sunspots are] never sighted at....
但是在這裡碰到了時態問題，原题想表達have never been sighted, 如果想要的话就必须把have been寫出來，省略原則之所以可以省略be，是因為be一般不重要，而這裡顯然不是這種情況。
这里如果要把have been写出来，那么就必须也补全主语，省略的话是主语谓语动词同进同出的，不会出现只省略主语或者只省略谓语动词的情况。这里sighted是过去分词。

逻辑主语和both and 平行

B项：at a cost 有 以...为代价 的意思，有歧义；此外，raising water bills so high that even environmentalists are beginning to raise alarms 作定语修饰cost, wordy expression.
可以这样理解吗？

[ref: gmatclub]
There are two ambiguous points:
1. Sentence C fails to show the causal relationship between 'the output of iron' and 'those technique improvements'.
2. the adverbial modifier in sentence C failed tell us when those techniques improvements happened.

E选项的within them这里的them应该指代的是谁呢？

tiger鲨鱼所捕食的小鲨鱼以鱼为食，而鱼对于渔业赚钱很重要

两个条件结合，3z

600m=0.0006k 500*0.0006=0.3