A选项以为是游说难推广；选项不能和文段信息孤立

在四个位置中选出2个位置（无顺序关系）给两列红玫瑰，一共是 C（4，2）结果是6，所以中间都是红玫瑰的概率是1/6.

这是我迄今为止见到的唯一一道宾语从句不加that的题，如果有其他这样的题希望有人回复我。

Ron对这道题表示：
is this problem really from GMATPrep?
it doesn't look like an official problem. you would want "that" here, as noted above. also, "it would be closing" would be better than "it was closing", since this was a future event at the time of the announcement.

老师能分析一下这道题吗：
PREP07 Test 2-2
In the Louisiana Purchase of 1803, the United States acquired 828,000 square miles for about four cents an acre, which more than doubled the country's size and that brought its western border within reach of the Pacific Ocean.

老师，您这是什么视频格式？我的电脑上无法显示。

B的with是修饰主句，错误，所以应该用定语从句

significant effect中性词

根据社区的需要来看

我也发现了一个很好的指代和修饰的例子：PREP07 Test 1-162

A. The government predicts that, for consumers and businesses that make a large number of long-distance calls, the Federal Communications Commission's recent telephone rate cuts will greatly reduce costs

B. The government predicts that costs will be greatly reduced for consumers and businesses that make a large number of long-distance calls by the Federal Communications Commission's recent telephone rate cuts

针对D，我不认为错误的原因在于when placed的逻辑主语错误。
when placed in a stimulating environment是状语从句的省略，变化为过去分词的形式，因此'placed in a stimulating environment'过去分词就近修饰名词mice
D最大的问题在于they的指代不清晰，有歧义地指代了neuron

will这里是noun

注意“a lack of a single yardstick”，说明single yardstick是存在的，只不过是不够，而no表示压根就没有

D选项：all had a written charter的主宾搭配是不正确的。不能是所有的13个殖民地共有一个宪章，每个殖民地应有自己的宪章。

此处的double并不是去比较两个数字，而是表示double v.使变为两倍

Unable主动发出

想请问一下这是什么推理模式啊？

调研了下，总结
1. 时态上，AE都有错，主句has／had appeared，后面从句was，就是错误的。这里从句应该与主语时态是一致的。
2 在we have now realized已经是现在完成，意味着在过去某个时间点之前我们都以为ozone是 immune from human influence，自然应该用过去完成时态。
3. it appeared后面加从句it blah blah是redundant，appear作为系动词，后面可以直接加形容词做表语。这样最为简洁清楚。

请问D选项为什么最后是is不是are？

题目是unlikely

核心词是purchase 不是950