例题： (1)
When rainbows appear, they are always in the part of the sky opposite directly the A B C D Sun.
答案：D
应改为：directly opposite.
解释：opposite 与the Sun 构成介宾短语, 修饰副词directly必须置于opposite之前 (2)
Amoebas are ---- small to be seen without a microscope. (A) far too (B) far and (C) so far
(D) as far as
答案：A
解释：空格前是句子的主谓语，空格处需要small的修饰语，B, C, D都不能修饰形容词, 故选A, 由副词too修饰small，副词far用来加深程度
第四节 容易混淆的词
hard (努力，副词) －hardly （几乎不，副词） close （接近，形容词） －closely（接近，副词）
near （接近，形容词） －nearly （几乎，副词）， nearby (adj.邻近的) most （大多数的，形容词） －mostly（主要地，大部分 副词）
late （迟、晚，形容词） －lately （最近，副词），later(adv.稍后的) high (高的，形容词) －highly (adv. 非常，大大的)
另外： friendly（友好的）， lovely(可爱的、有趣的)，尽管词尾有ly, 但是都是形容词 例题： (1)
Chief Joseph La Flesche, a vigorous Omaha leader, worked hardly to make his nation A B a proud and progressive one. C D
答案：B
应改为：hard
解释：hard和hardly都是副词，前者表示努力地，后者表示几乎不，依据题意应改用hard 词汇：vigorous: 精力充沛的，progressive: 进步的
(2)
Glaciers that develop nearly the North and South Poles advance into the sea, break A B C D into pieces, and become icebergs.
答案：B
应改为：near
解释：nearly是副词，意为几乎，在此句中讲不通，改为介词near才可与名词the North and South Poles构成地点状语
词汇：glacier: 冰河， iceberg: 冰山
(3)
Those electrons most closely to the nucleus are held there by electromagnetic force. A B C D
答案：B
应改为：most close
解释：副词closely 不能修饰名词electrons, 应改为形容词, close to 构成形容词短语, 作electrons的后置定语
词汇：electron: 电子, electromagnetic: 电磁
第四章 介词
介词在英语中有着举足轻重的地位，其数量不多，拼写也不复杂，但要准确的把握其用法却非易事，介词的恰当使用常常成为令英语学习者头疼的问题。TOEFL中常考知识点是动词后面到底跟不跟介词，常用介词搭配, 常用动词与介词搭配
第一节 常用介词
考点一 常用介词的用法
常用介词包括简单的，
如：in, on, at, from, to, like, of, for, after, before, by, with, to, since, between, etc.； 还有一些组合的，如：into, onto, out of, throughout, within, upon, etc. 这些词的具体用法需要下功夫搞清，在TOEFL题中都有所体现。
例题： (1)
----one time, Manchester, New Hampshire, was the home of the most productive cotton mills in the world. (A) On (B) At (C) By (D) To
答案：B
解释：据选项可知需填介词，词组at one time意为“曾经、一度”，符合句意。
(2)
Saint Elmo's fire is a luminous blue discharge of electricity sometimes seen when a A B C D thunderstorm.
答案：D
应改为：in.
解释：when是连词，一般只引导从句，应该用介词引导宾语
考点二 及物动词和不及物动词
在改错题目中，经常会出现混淆及物动词和不及物动词， (1) 不及物动词后面必须要加上介词，比如go Guangzhou（到广州去），这样表达是不对的，必须改为 go to Guangzhou
(2) 而及物动词后面不能随意加上介词，因为及物动词后面可以直接接名词 比如 find the mistake (寻找错误) ， 不应该说 find for the mistake
例题： (1)
What makes for human skeleton hard and strong is the presence of the metallic A B C D element calcium. 答案：A
应改为：human
解释：make是及物动词，直接加宾语，for是多余的
词汇：skeleton: 骨骼, metallic: 金属的, calcium: 钙
(2)
The situation comedy has proved to a remarkably durable commercial television A B C D format. 答案：B
应改为：to be a / a.
解释：及物动词prove可直接加名词或不定式作宾语
词汇：situation comedy: 情景喜剧, durable: 持久的, format: 形式
第二节 介宾短语
介词不能单独使用，而必须和其他词连用，这些词称作介词的宾语，它们共同构成的介宾短语常在句中作状语，作名词的后置定语，有时作某些动词的宾语补足语
考点一 名词作介词宾语
大部分介词的宾语都是由名词(包括代词)充当的，如：under the tree, during the day, 这一考点在题中多次出现
例题： (1)
The development of mechanical timepieces spurred the search for ----with which to regulate them. (A) more accurate than sundials (B) more accurate sundials (C) sundials more accurately
(D) more accurately than sundials
答案：B
解释：search for缺少宾语, 只有B是表达无误的名词词组, 可以作宾语；其他选项的比较形式都有错。 (2)
Different species of octopuses may measure anywhere from two inches to over thirty A B C feet in long. 答案：D
应改为：in length.
解释：long 是形容词, 不能单独接在介词之后, 其名词形式length与in构成介宾短语, 表示长度
考点二 动名词作介词宾语
名词作宾语时，之后不能再接宾语，这一缺陷可由动名词弥补。 如：before doing the job , after getting back
改错题中常把应该用动名词作宾语的地方误用为名词或不定式，需留心陷阱 例题： (1)
The Conestoga wagon, used for to carry heavy loads over long distances, originated A B C
around 1725 in a region of Pennsylvania occupied by the Conestoga Indians. D 答案：A
应改为：carrying.
解释：不定式不能作for的宾语, 改为动名词即可
(2)
Copper sulfate, spread in judicious amounts, kills algae ----harming fish or aquatic invert-ebrates. (A) does not (B) but does no (C) except (D) without
答案：D
解释：harming 是动名词形式, 因此要求前面的词是介词或可接动名词的动词. A B 可首先排除; C 虽是介词, 但与句意不符.
(3) Mary Ann Hardy was known for her skill to paint miniature watercolor portraits A B C on ivory. Ｄ
答案：B
应改为：in painting
解释：后置定语修饰名词，什么方面的技能，不能用不定式。 考点三 连接从句或不定式
介词之后还可以接宾语从句或不定式短语，但要借助于 连接代词 (如：what , which, whom) 或连接副词 (如：how, when，where)
例句： I knew nothing about how he got the green card. She's pretty hesitant about which one to choose.
例题： (1)
The Cubists were concerned with how----a given subject from different points of view simultaneously. (A) represented
(B) do they represent (C) to represent (D) representing
答案：C
解释：介词with后面的宾语不完整, C 是不定式短语作宾语. A D都不足以和how构成宾语从句; B不应用疑问句语序, 若去掉do则是正确的
(2)
The scholarly interest in perception stems largely from questions about the sources and validity of what ----.
(A) it is known as human knowledge (B) is known as human knowledge (C) known human knowledge
(D) is human knowledge known
答案：B
解释：介词of的宾语残缺, B 构成宾语从句, 包含短语be known as；A多主语it; C 无法与what契合; D 语序错误
注意：介词后面不能够接 that 所引导的从句，除非in that连起来作为特殊的状语从句引导词，表原因 (3) (Exer1_21_31)
Soprano Julia Migenes-Johnson believes in that her Latin American background A B
helped her interpret the role of the Spanish character Carmen in a 1984 opera film. Ｃ D
答案： A
应改为：believes
解释：介词后面一般不能够接that 引导的从句。除非in that连起来
(4)
Hovercraft, or air-cushion vehicles, are unusual ---- travel over land and water on a layer of air .
(A) they (B) in they (C) that they (D) in that they
答案：D
解释：空格前是句子的主谓语，空格后是谓语结构，空格处需要从句引导词及从句主语，只有D符合题意，in that是特殊的状语从句引导词，表原因 词汇：hovercraft: 水翼船, cushion: 垫子
第三节 介词固定搭配
介词和动词、形容词、名词等词的搭配是掌握介词用法的难点和关键，必须下大功夫牢记，TOEFL题中大量考察介词搭配问题，是准备的重点之一，下面对常见常考搭配稍作总结，可作复习的参考，但因篇幅所限，不可能面面俱到，还需考生多注意平时积累
一、常搭配使用的介词和介词短语 1. from?to /till /until
2. because of, on account of (由于), by means of, in front of, in spite of (=despite), instead of, in honour of (为纪念，为庆祝)，in danger of (在?.危险之中)
3. according to, due to, with regard to, prior to, owing to, , in relation to, in response to, to a great extent, in addition to(=besides)
4. together with, along with, in connection with, in comparison with, apart from 二、与on /upon搭配
1. act on, rely on, depend on, feed on, comment on, concentrate on, rest on, in 2. be based on, be keen on, be dependent on
The boy is keen on mathematics. (这个男孩对数学感兴趣)