在句子中充当除谓语以外的句子成分的动词形式叫作非谓语动词。非谓语动词分为三种形式∶动名词，不定式和分词。
(一) 分词
现在分词和过去分词的区别
①、用于句首作状语，现在分词表示主动，过去分词表示被动
例：Won its war for independence in 1783, the United States then
A
struggled to establish its own economic and financial system.
B C D
分析：分词作状语，主要看是主动还是被动，美国赢得应该是主动,所以A错，改won为winning
②、用于名词后面作后置定语，现在分词表示主动，过去分词表示被动
例：In the nineteenth century the Mohave Indians lived in
A B
the Northern Hemisphere grew their crops on river bottom lands.
C D
分析：B错，生活在什么地方的人，人生活是主动，因此改为living
一些动词后面必须用doing
对于加doing的词来说，考试中一般出现一个，下面这些词都是要加doing的，请考生牢记。
mind, finish, enjoy, celebrate, adjust
advocate, suggest
delay, quit
forgive(原谅)，tolerate，
avoid, escape(逃避)
spend+名词+doing;
have trouble/difficult/a problem/ +doing
例：Long before the dawn of recorded history, humans celebrated to harvest their
A B C D
crops.
分析：D错，应改为harvesting。及物动词celebrate直接带名词、名词短语或动名词短语作宾语，故将to harvest改为harvesting。
例：Some experts have advocated to bring that country into the talks,
A B
to revive the intermittent dialogue that began after the 1967 Middle East War.
C D
分析：A错，advocate 后面直接跟doing, 改为advocate bringing
(二) 不定式
A. 动词不定式的省略
①、help后面可以省略to
help to do
help sb. to do
例：A good exercise program helps teach people to avoid
A B
the habits that might shorten the lives.
C D
分析：D错，应改为their. 定冠词在句中不如代词所有格明确，如果lives后面有定语就可以用the。注意(A)并没有错，help后面可以接不带to的不定式。
②、使役动词后面要省略to, 这样的动词只有三个
make,
let,
have sb. do sth
注意get不是使役动词，get sb. to do sth.
例：A conductor used signals and gestures to let the musicians
A B
to know when to play various parts of a composition.
C D
分析：let是使役动词，后面不需要to, C改为know
③、感官动词
hear, feel, watch, see, notice, observe
see sb do sth. 强调过程
see sb doing sth 正在做某事
B. 动词不定式的固定用法
(1)表示第一人
the first woman to do sth.
(2)表示迫使的动词
一般考三个， allow/ enable/ call, +sb. + to do
例：Besides providing clues to the nature of atoms, mineral analysis
A B
allows to speculate geologists about the ancient Earth.
C D
分析： do是固定短语,allow的宾语应在不定式之前,即把C改为: allow geologists to speculate。
(3)表示倾向…的形容词
be more likely to do 更有可能作某事
be inclined to do倾向于做某事
be liable to do 易于…的
be apt to do
(4)表示目的的名词，一共有7个这样的.词，这一条也是最重要的。
固定的句式：
the purpose , the purpose of sth is to do sth.
the objective 目标
aim
goal
reason理由
function功能
intension意图
例：The function of Louis Sullivan's architecture was providing
A
large uninterrupted floor areas and to allow ample light into the interior.
B C D
分析：the function to provide, A错
例：The chief goal of biochemistry is for understanding the structure
A
and behavior of the carbon-containing compounds
B
that make up various components of a living cell.
C D
分析：the chief goal is to understand, A错
(5) 其他同根名词
ability to do 受到be able to 的影响
attempt to do 企图
decision to do 决定, 受decide的影响
ambition,
be ambitious to do
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