关于in fact的逻辑含义，托福阅读界一直都持有一个共识：in fact要么表递进，要么表转折。

但是，我还是觉得需要去验证一下，不然不放心。所以我就查询了TPO，把所有文章中用到in fact的情况都摘了出来。然后，我对每个in fact进行了分析，最后得出了一些我自己的结论。

不敢说大家之前的结论是错的，但是有一些新的想法和细节不亲自研究还是发现不了的。

一、in fact单独使用表转折的情况很少，我只找到一个例子:

TPO 16-2 Development of the Periodic Table

Paragraph 2

When the German chemist Lothar Meyer and (independently) the Russian Dmitry Mendeleyev first introduced the periodic table in 1869-70, one-third of the naturally occurring chemical elements had not yet been discovered. Yet both chemists were sufficiently farsighted to leave gaps where their analyses of periodic physical and chemical properties indicated that new elements should be located. Mendeleyev was bolder than Meyer and even assumed that if a measured atomic mass put an element in the wrong place in the table, the atomic mass was wrong. In some cases this was true. Indium, for example, had previously been assigned an atomic mass between those of arsenic and selenium. Because there is no space in the periodic table between these two elements, Mendeleyev suggested that the atomic mass of indium be changed to a completely different value, where it would fill an empty space between cadmium and tin. In fact, subsequent work has shown that in a periodic table, elements should not be ordered strictly by atomic mass. For example, tellurium comes before iodine in the periodic table, even though its atomic mass is slightly greater. Such anomalies are due to the relative abundance of the "isotopes" or varieties of each element. All the isotopes of a given element have the same number of protons, but differ in their number of neutrons, and hence in their atomic mass. The isotopes of a given element have the same chemical properties but slightly different physical properties. We now know that atomic number (the number of protons in the nucleus), not atomic mass number (the number of protons and neutrons), determines chemical behavior.

这里，in fact前讲到化学家们认为原子质量严格地决定了元素在元素周期表里的位置，in fact后讲到后来研究发现原子质量不完全决定了元素在元素周期表里的位置。这是很明确的转折逻辑。

其他的in fact表转折的情况，都是通过与一些转折逻辑词联用的方式来达到转折的效果。比如：

Hills and mountains are often regarded as the epitome of permanence, successfully resisting the

destructive forces of nature, but in fact they tend to be relatively short-lived in geological terms.

Mathematical models of ecosystems likewise suggest that diversity does not guarantee ecosystem stability—just the opposite, in fact.

However, more recent data imply that at least some parts of the planet did in fact experience long periods in the past during which liquid water existed on the surface.

Just as painted designs on Greek pots may seem today to be purely decorative, whereas in fact they were carefully and precisely worked out so that at the time, their meaning was clear, so it is with Chinese pots.

这种情况是会有可能出插入题的，比如：

TPO 18-2 The Mystery of Yawning

Another flaw of the tiredness theory is that yawning does not raise alertness or physiological activity, as the theory would predict. When researchers measured the heart rate, muscle tension and skin conductance of people before, during and after yawning, they did detect some changes in skin conductance following yawning, indicating a slight increase in physiological activity. However, similar changes occurred when the subjects were asked simply to open their mouths or to breathe deeply. Yawning did nothing special to their state of physiological activity. Experiments have also cast serious doubt on the belief that yawning is triggered by a drop in blood oxygen or a rise in blood carbon dioxide. ■Volunteers were told to think about yawning while they breathed either normal air, pure oxygen, or an air mixture with an above-normal level of carbon dioxide. ■If the theory was correct, breathing air with extra carbon dioxide should have triggered yawning, while breathing pure oxygen should have suppressed yawning. ■In fact, neither condition made any difference to the frequency of yawning, which remained constant at about 24 yawns per hour. ■Another experiment demonstrated that physical exercise, which was sufficiently vigorous to double the rate of breathing, had no effect on the frequency of yawning Again the implication is that yawning has little or nothing to do with oxygen.

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

This, however, was not the case.

Where would the sentence best fit?

本题正确答案为C。正是however和in fact的联用。

二、in fact 多数情况下表递进，可以引出具体展开，也可以引出结论。

首先，我们需要明确一下递进到底是什么逻辑。

百度百科是这样说的：所谓递进关系，是指复句中后一分句须以前一分句为基点、并在程度或范围上比前一分句有更进一层的语义关系。

我个人认为中文的“甚至”(就是英文的even)是非常典型的递进关系。比如，我很喜欢水果，甚至每天吃两次水果。从这个例子里我们可以发现，递进之后的内容实际上相较之前的内容来说是更具体的信息。也就是说，递进前是相对宽泛的信息，递进后是相对具体的信息。而且，前后的信息从逻辑上来讲是不能矛盾的，逻辑方向是一致的：我每天吃两次水果和我很喜欢水果的逻辑方向是一致的。

表达类似逻辑的情况确实在TPO里算是多数，多体现为前文说出一个结论性的句子，in fact之后会引出具体的进一步的证据。比如这个插入题：

TPO 8-1 The Rise of Teotihuacán

【Paragraph 1】The city of Teotihuacán, which lay about 50 kilometers northeast of modern-day Mexico City, began its growth by 200-100 B.C. At its height, between about A.D. 150 and 700, it probably had a population of more than 125,000 people and covered at least 20 square kilometers. ■It had over 2,000 apartment complexes, a great market, a large number of industrial workshops, an administrative center, a number of massive religious edifices, and a regular grid pattern of streets and buildings. ■Clearly, much planning and central control were involved in the expansion and ordering of this great metropolis.  ■Moreover, the city had economic and perhaps religious contacts with most parts of Mesoamerica (modern Central America and Mexico). ■

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

In fact, artifacts and pottery from Teotihuacán have been discovered in sites as far away as the Mayan lowlands, the Guatemalan highlands, northern Mexico, and the Gulf Coast of Mexico.

Where would the sentence best fit?

正确插入的位置D的前句是一个结论性的句子，插入句in fact之后正好是具体的证据。

比如还有这道插入题：

TPO 31-2 Early Childhood Education

【Paragraph 6】Not everyone agrees that programs that seek to enhance academic skills during the preschool years are a good thing. ■In fact, according to developmental psychologist David Elkind, United States society tends to push children so rapidly that they begin to feel stress and pressure at a young age. ■Elkind argues that academic success is largely dependent upon factors out of parents' control, such as inherited abilities and a child's rate of maturation. ■Consequently, children of a particular age cannot be expected to master educational material without taking into account their current level of cognitive development. ■In short, children require development appropriate educational practice, which is education that is based on both typical development and the unique characteristics of a given child.

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

According to Elkind, not only does this cause the child emotional distress, it also fails to bring the intended cognitive gians. 

Where would the sentence best fit?

这题正确答案是B。虽然这个插入题不是直接考in fact，但是位置A之后有一个in fact，这个in fact之后的内容就是前一句结论性句子的一个具体证据。所以插入句放到A这里会打破这种递进的逻辑关系，所以不能放A。

但是，还有一种in fact前后逻辑一致的情况，in fact不是引出具体展开，而是引出结论。

这种情况里，in fact之后没有给出针对前文的具体信息，反而是引出了一个结论性句子，也就是对前文进行了总结。比如：

Swimming Machines

Because they are always swimming, tunas simply have to open their mouths and water is forced in and over their gills. Accordingly, they have lost most of the muscles that other fishes use to suck in water and push it past the gills. In fact, tunas must swim to breathe. They must also keep swimming to keep from sinking, since most have largely or completely lost the swim bladder, the gas-filled sac that helps most other fish remain buoyant.

这段文字中的in fact之后并不是一个具体信息，而是一个结论。

再比如这道插入题：

TPO 11-1 Ancient Egyptian Sculpture

【Paragraph 4】Apart from statues representing deities, kings, and named members of the elite that can be called formal, there is another group of three-dimensional representations that depicts generic figures, frequently servants, from the nonelite population. ■The function of these is quite different. ■Many are made to be put in the tombs of the elite in order to serve the tomb owners in the afterlife. ■Unlike formal statues that are limited to static poses of standing, sitting, and kneeling, these figures depict a wide range of actions, such as grinding grain, baking bread, producing pots, and making music, and they are shown in appropriate poses, bending and squatting as they carry out their tasks.■

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. 

In fact, it is the action and not the figure itself that is important.

Where would the sentence best fit?

本题正确答案为D。同样，插入句里的in fact引出的也是一个结论性的句子，并不是具体信息。

所以，我们可以总结一下：

1. in fact少数情况下表达转折，但是一般会连带着别的转折逻辑词。

2. in fact多数情况下表递进。表递进的情况下，多数是in fact后引出具体信息，少数情况下是in fact后为结论性信息。

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