To see is to believe/ To work means to earn a living.
2. 另一种情况主语是以aim, duty, hope, idea, happiness, job, plan, problem, purpose, thing, wish等为中心的名词，或以what引导的名词性从句，不定式表语对主语起补充说明作用
His wish is to buy a luxurious car in the near future. / The boss's plan is to start building the skycraper immediately. / What I want to say is to get rid of the plan forever.
11) The function of Louis Sullivan's architecture was providing ［A］ large uninterrupted floor areas ［B］ and to allow ample light ［C］ into the interior ［D］ .
12) The most important ［A］ thing is negociate ［B］ with them about ［C］ the future of ［D］ the plant.
13) The flexibility of film allows the artist unstrained imagination to the animation of cartoon characters.
［A］ to bring［B］ bringing［C］ is brought［D］ brings
14) Billie Holiday's reputation as a great jazz?blues singer rests on her ability emotional depth to her songs.
［A］ be giving［B］ are given［C］ being given［D］ to give 另外，有些词的不定式定语有主谓关系，如除了上述例句以外，还有些词常跟不定式作定语。这些词主要有decision (to make), (a) need (to eat), opportunity (to speak),reason(to learn a foreing language), time (to sth)等。
15) Alice was having ［A］ trouble to control ［B］ the children because there were ［C］ so many ［D］ of them.
16) There are so many reference books for matriculation of postgraduate and I haven't decided which book .
［A］ to buy［B］ buy［C］to be buying［D］ buying
17) Astronauts can be affected by loneliness for they have to sit in the spacecraft for weeks with very little and no one .
［A］ to do … to talk［B］ doing … to talk to
［C］ to do … to talk to［D］ doing… to talk
He has a lot of trifles to deal with./ I had got no place to live in./That girl has nothing to worry about./the subject to concentrate on. / He has a strict teacher to listen to. / She has four children to look after. / She had a sick mother to live with. / This is the very person to sell your ticket to.
18) Although the lecture had already been on for five minutes, I still was not able to find a chair .
［A］ to sit［B］ for to sit on［C］ to sit on［D］ for sitting
4. 一些表示企图、努力、倾向、目的、愿望、打算、能力、意向等意义的名词后面要求接不定式作其定语，如：ability, attempt, effort等
19) During ［A］ the 19th century scientists found ［B］ that when certain parts of the brain were damaged ［C］ men lost the ability doing ［D］ certain things.
20) What is new, however, is the scientific attempt whether other planets beyond our own have given birth to advanced civilizations.
［A］ discover［B］ discovers［C］ discovering［D］ to discover
21) Surely her daughter would make an even bigger effort her?
［A］ please ［B］ pleased ［C］ to please ［D］ having pleased
22) its plans to promote disarmaments，the party has decided to establish a campaign headquarters with Benjamin Seaman as its leader.
［A］Although［B］To carry out［C］Except that［D］ Make
23) pure lead，the lead ore is mined，then smelted，and finally refined.
［A］ Obtaining［B］ Being obtained［C］ To obtain［D］ It is obtained
24) When they met，Leonardo and his enemy were fighting .
［A］killed each other［B］killing each other［C］to be killed each other
［D］to kill each other
He must be cripple not to walk by himself./It seems that the employee didn't sleep at all to be so sleepy in the early morning. / What have I done for you to deserve such an amount of money?
还有固定搭配的不定式表示结果：so…as to; such(…) as to …; enough to…; too…to…; in order to … 等
We have got so plenty of food as to treat our guests./ Is that room big enough to seat all of us?/ He is too young to fit that job.
It's very kind of you to say so. / I am pretty pleased to hear the news that you are elected as the president of the club. / I'm sorry to interrupt you. / They are quite surprised to see the great changes taking place in the area.
在下列表示能力、愿望、倾向等语义的形容词后边也要接不定式：able(但其同义词" capable"后面要接"of+动名词")，anxious, eager, glad, inclined(倾向于)，liable, likely, pleased, ready等。
25) Certain ［A］ minerals are magnetic and are able to detected ［B］ by instruments that measure ［C］ differences in the Earth's magnetic fields ［D］《英语语法详解 动词不定式（三）》由英语编辑整理,更多请访问:https://www.liuxue86.com/english/