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 feet in long.
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, originatedaround 1725 in a region of Pennsylvania occupied by the Conestoga Indians.
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 on ivory.
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。
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