7-5. Инфинитив как обстоятельство

Инфинитив может употребляться в роли обстоятельства.

1. Выражая цель (одно действие должно последовать за другим):

He came to London to look for work.
I have come to apologise.
I sent Mrs Bacon a bunch of flowers to thank her for the party.
I sat down to rest. (не: I sat down for resting / for to rest.)
He went abroad to forget.
I'm going to Austria to learn German.
To switch on, press red button.

2. Несколько более сложная конструкция получается добавлением so as или in order перед инфинитивом (чтобы избежать возможной двусмысленности из-за того, что инфинитив имеет и другие варианты использования):

Some people refuse/hesitate to say what they think.
Some speakers hesitate (so as) /=(in order) to choose the right word.

The lecturer stopped talking at last.
He stopped (so as)/=(in order) to talk to me after the lecture.

Our host left us, (so as)/=(in order) to pay the bill. (He paid it)
He invited us to a restaurant then left us to pay the bill. (We had to pay it)

Еще примеры:

He got up early in order to have time to pack.
I watched him in order to know more about him.
I moved to a new flat so as to be near my work.

In order to / so as to часто необходимо перед «отрицательными» инфинитивами:

I'm going to leave now, so as not to be late (неверно: I'm going to leave now, not to be late.)

Если речь идет о вовлечении в действие кого-либо, то можно использовать for + имя собственное/местоимение:

I left the door unlocked for Harriet to get in.

3. Выражая неожиданные последствия:

He went home to find his old friend George waiting for him.
I arrived home to find that the house had been burgled.
(в отличие от цели в ‘He went home to get his coat’)

С помощью only можно выразить негативное восприятие последствий:

He went home (only) to find his house in ruins.
At last we got to Amy's place, only to discover that she was away.
He spent four years studying, only to learn that there were no jobs.

4. Инфинитивные обороты соответствуют придаточным обстоятельственным предложениям

(а) цели (при условии, что подлежащее и время действия – общее в обеих частях):

He worked all night [so that he could get the job done in time].
He worked all night [so as to get the job done in time].

(b) придаточный клоз результата:

His work was so good that it made him internationally famous.
His work was so good as to make him internationally famous.

He was in such bad health [that he was obliged to resign].
He was in such bad health [as to be obliged to resign].

4. To hear her talk, you'd think ...

Инфинитивы глаголов see и hear можно употреблять, чтобы выразить причину ошибочного представления о чем-либо. После такой конструкции обычно идет you'd think или похожее выражение:

To see them, you'd think they were married. But they only met yesterday.
To see him walk down the street, you'd never know he was blind.
To hear her talk, you'd think she was made of money.