a： them指代不清
b：many hundreds of monasteries.赘余，去掉many；
c：同位语插入，dot点缀，are dotting错误时态尴尬；
d：时态：many of which are chiseled from solid rock centuries ago.应该 过去时
especially=to an unusually high degree ,or,more so than comparable thing.(something unusual)
specially =done in special manner(on purpose) 这里用especially表示其污染的程度更深。DE错。
看一下Ron的解释：
* "forbid ... to" is more or less universally preferred to "forbid ... from" in formal written english, so i would assume that the gmat will follow the same preference.
a couple of other points:
* "prescribe drugs for their patients" is much better than "prescribe their patients drugs" (which would be fine in spoken language, but is at best awkward and at worst ambiguous when written)
* "prescribing privileges" is better than "the privilege to prescribe / privilege of prescribing", especially if the latter is placed at the end of the underlined part (as it is in choice a). the problem with the wording in choices (a) and (d) is that it's ambiguous: "...the privilege of prescribing to ... psychologists" could be taken to mean that the prescriptions themselves are being written for psychologists.
主语fossils和谓语动词made之间不应添加逗号，例如：
(1) I play cards.
(2)** I, play cards.
句(2)是错误的，不能用逗号隔开主语和谓语动词。（有时因有插入语导致谓语动词身前有逗号，这不矛盾。因为那个逗号是用来隔开插入语和主句的，不是用来隔开主语和谓语动词的。语法上不允许有目的是为了隔开主语和谓语动词的逗号）
首先，由于本选项的dated是过去分词（不可能是过去时，因为date理应是被动语态，若是谓语动词的过去时应该用were dated），所以其引导的部分应该同found in Puerto Rico in 1991平行。鉴于此，and dated at 34 million years old身前和身后的逗号是不应该加的（只有三者平行或者两个完整的句子间的and前才应该加逗号）。
aving done 结构肯定是做状语的修饰主句的动作的，不是定语来修饰名词的。如果你having done结构只是来修饰一个名词的，那何谈和名词的先后顺序的？ 那什么时候 现在分词doing 做定语呢？在GMAT中 如果 doing结构不加逗号直接放在名词后面，往往都是做定语的，所以我们可以推断出: having done 是永远不会做定语的。具体来说 也就是永远不会没有逗号而存在。
1. men and women，所以要用themselves，排除CE
2. D选项还原 it had previously been considered of men and women they were incapable of discerning truth for themselves ，首先引导从句省略了that，其次句意完全读不通，所以排除
3. having been done只能做状语
"evidence to suggest" and "evidence that suggests" are both acceptable in this sort of context. neither is a basis for elimination. normally you would see "evidence that suggests..." however, they've used "evidence to suggest..." here, in order to avoid writing evidence THAT suggests THAT xxxxx. not because it's wrong -- just because it's ugly.
not only is Jupiter three times as massive as Saturn, the next largest
选项还原成为正常语序：Jupiter is not only three times as massive as .. 和 but also 后面的 possesses four of the largest satellites, or moons, in our solar system.不平行
Singing a tuneless song, there comes Matt. 这样倒装不对
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a： them指代不清b：many hundreds of monasteries.赘余，去掉many；
c：同位语插入，dot点缀，are dotting错误时态尴尬；
d：时态：many of which are chiseled from solid rock centuries ago.应该 过去时