Some psychiatric studies indicate that among distinguished artists manic depression and major depression are ten to thirteen times more prevalent than in the population at large.
=Some psychiatric studies/ indicate/ that among distinguished artists/ manic depression and major depression/ are ten to thirteen timesmore prevalent/ than in the population at large.
#一些心理研究/表明/在杰出的艺术家中/躁狂抑郁症以及主要的抑郁症/高出10至13倍/比整个人口(的平均水平)。
* manic depression属于认识就反映不认识就过去的词类。根据句意at large 本来可以不琢磨，但是笔者将其加上黑体字，就是想告诉读者，英语中有很多俚语，俗语是不能靠猜测而知道其意的，这类词语要靠平时积累，不过好在GRE GMAT中这种短语并不是很多。
Until quite recently, American presidents lived in a world in which the public and private realms of their lives were largely separate, in which the press cooperated in maintaining the distinction, and in which Americans judged national leaders without receiving, or expecting, intimate information about them.
=Until quite recently, American presidents/ lived in a world/ in which the public and private realms of their lives/ were largely separate/, in which the press/ cooperated/ in maintaining the distinction/, and in which Americans/ judged national leaders/ without receiving, or expecting, intimate information about them.
#直到最近为止，美国总统/一直生活在这样一个世界里/在那里他们生活的公共和私人领域被大大的分开了/，在那里媒体/合作/保持这个区分/在那里美国人/评价国家领导人/不接受或期待他们的隐私。
*这句话虽然很长，但不难理解，都在说美国总统生活在什么样的世界。唯一一个难点是Until的理解。在这句话中用了live这个动词，根据Until 的使用规则，如果后面接的是延续性动词，如live，则表达动作一直进行，直到Until后的的时间为止。所以，句子的意思是美国总统以前一直生活在这样的世界中，而最近他们不在生活在这样的世界里了。
