不定式作定语
不定式做定语通常要放在被修饰的词后,往往表示未发生的动作.例如：
I have a lot of work to do.我有许多事要做.
There was nothing to bring home that morning.那天早上（他回家时）两手空空.
不定式作补语
1） 有些有动词+宾语+不定式的结构.例如：
advise
allow
cause
challenge
command
compel
drive 驱使
enable
encourage
forbid
force
impel
induce
instruct
invite
like/love
order
permit
make
let
have
want
get
warn
persuade
request
send
tell
train
urge
例如；
Father will not allow us to play on the street.父亲不让我们在街上玩耍.
The officer ordered his men to fire.长官命令士兵开火.
注意：有些动词如make,have,get,want等可用不定式作做宾补,也可用分词作宾补.现在分词表达主动,也表达正在进行,过去分词表达被动.
2) 有些有动词+宾语+不定式的结构,不定式的动词往往是be,不定式一般可以省去.例如：
consider
find
believe
think
declare（声称）
appoint
guess
fancy（设想）
guess
judge
imagine
know
例如：We believe him to be guilty.我们相信他是有罪的.
We know him to be a fool.我们知道他是个笨蛋.（to be 不能省去）
3) 有些动词可以跟there +to be的结构.例如：
believe
expect
intend
like
love
mean
prefer
want
wish
understand
例如：
We didn't expect there to be so many people there.我们没料到会有那么多人在那里.
You wouldn’t want there to be another war.你不至于想让另外一场战争发生吧.