四、非谓语动词

(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.
　BCD
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,
　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　BCD
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.
CD
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
AB
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：allow...to 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 lieable 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.
CD
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　
　effort
例：For ancient people, myths were often attempts explanation
AB
　 catastrophic events such as volcanic eruptions.
C　D
分析：B错，应改为to explain。 attempts后应跟动词不定式短语表目的，故将名词explanation改为to explain。
例：In the early 1960's the Civil Rights movement made great
A　B
　 efforts for registering members of minorities to vote.
　CD
分析：efforts to register, C错

C. 动词不定式的其他用法

(1) be to do 表示已安排好或者注定要发生的动作，属于将来时态的范畴
She and Anne are to meet at two o'clock.

(2)不定式的完成式为“to have done”，表示不定式的动作在谓语动作之前发生，这个完成式通常表示一般过去时
I am glad to see you.
I am glad to have seen your mother yesterday.
yesterday是一般过去时，修饰have seen.

(3) 形容词后面使用动词不定式，主动表示被动
It is difficult to decide