在新
托福阅读的考查中，每篇文章必会出现一类题，叫做"Insert Text Questions"，即插入句子题(简称插入题)。考试中，考生会遇到一句话，问该句插入文中哪里最合适。如下面例题：
The raising of livestock is a major economic activity in semiarid lands, where grasses are general the dominant type of natural vegetation. The consequences of an excessive number of livestock grazing in an area are the reduction of the vegetation cover and the trampling and pulverization of the soil. This is usually followed by the drying of the soil and accelerated erosion.
Look at the four squares that indicate where the following sentence can be added to the passage。
This economic reliance on livestock in certain regions makes large tracts of land susceptible to overgrazing。
Where would the sentence best fit?
(选自Official Guide P73)
按照ETS官方指南上的解析，这类题型重点考查英文句子间的逻辑语义关系，即英文中句子与句子是如何衔接在一起的。所以，只要掌握了英语句子间的衔接手法(cohesive devices)，这种问题便可迎刃而解。
那么，英文句子有哪些衔接手法呢?
主要分为以下四种。
1. 代词(Pronouns)
具体包括人称代词、指示代词和关系代词等(personal, demonstrative, relative, etc)。在上下句的关联中，代词是最为紧密的一类词。当作者再次谈及上句相关话题时，为了避免重复，遵循语言学的最简单化原理，作者会用代词指代该话题词。例如，
Speaking a foreign language is an enormous asset in the modern world. This is why so many junior high schools are now offering language classes。
Today's teachers are faced with a stark choice. They must decide whether to teach in a way that helps student pass standardized exams or teach in a way that actually helps students learn。
2. 定冠词the + 名词(specific articles+nouns)
名词所指对象第一次出现时，用不定冠词a连接，当后句再次提及该名词对象时，为了表示它和前一句名词是同一关系，会用定冠词the引出。例如，
A woman is walking into our classroom. The woman is our teacher。
3. 重复话题词或同义近义改写(Repetition, synonym, or slight variation of a word)
上下句的衔接也可以通过重复话题词实现，或者是对该话题词进行相关改写。例如，
To foster healthy relationships between children in a classroom, teachers should provide time for games and fun activities. Having healthy relationships with their peers helps children gain confidence useful in other parts of their lives. (重复话题词)
Before choosing a public or private school for their children, parents should take into account the cost. The price of a private school is usually much higher than that of a public school. (话题词同义改写)
4. 过渡性词和词组(Transitional phrases/transitional adverbs)
上面讲到的三种句间关系属于隐性关系。隐性关系通过上下句的语义关系体现。现在，我们要讲的是句子间的显性关系，即通过明显的逻辑连词或副词来体现句间关系。这些显性关系词包括以下类别。
4.1 时间关系
then, next, later, finally, etc。
4.2 因果关系
therefore, consequently, as a result, etc。
4.3 转折关系
however, but, yet, nevertheless, on the other hand, etc。
4.4 解释关系
that is, in other words, etc。
4.5 举例关系
for instance, for example
例如，Peers and older siblings have a major influence on how school children behave. For instance, young children often repeat bad words they hear from their friends or brothers and sisters。
有了上面的理论铺垫，我们再来看小插题就容易得多了!
例如，前面给出的那道例题，
The raising of livestock is a major economic activity in semiarid lands, where grasses are general the dominant type of natural vegetation. The consequences of an excessive number of livestock grazing in an area are the reduction of the vegetation cover and the trampling and pulverization of the soil. This is usually followed by the drying of the soil and accelerated erosion.
Look at the four squares that indicate where the following sentence can be added to the passage。
This economic reliance on livestock in certain regions makes large tracts of land susceptible to overgrazing。
Where would the sentence best fit?
我们先读给出的这句话--This economic reliance on livestock in certain regions makes large tracts of land susceptible to overgrazing. 这个句子使用的衔接手法(cohesive device)属于代词指代前文话题词。this后面的名词economic reliance on livestock一定在上一句里出现。于是，搜索段落，答案锁定在第二个方框前的那一句The raising of livestock is a major economic activity in semiarid lands, where grasses are general the dominant type of natural vegetation。这句话与被插入的句子话题一致，都是在讲"经济上依赖牲口"这件事，所以应插入第二个方框。
同理，以下考题，请考生自测。答案见文末。
Extinct but already fully marine cetaceans are known from the fossil record.How was the gap between a walking mammal and a swimming whale bridged?Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans。
