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For 1
We can sometimes use for + ing to talk about the purpose of a thing. When we do, it means the same as to + infinitive.

What is that for? It is for opening envelopes
This bell is for calling the waiter.
This bell is to call the waiter.
 

When we talk about the purpose of somebody's actions, we cannot use for + ing.

I went there to ask for help.
You will have to queue a long time. to get tickets.
 

However, it is sometimes possible to use for + noun for this.

I went there for help.
You will have to queue a long timefor tickets.
 

We can also use for + object + infinitive to talk about a purpose.

I gave her a notebook for her to write down new English words she found.
They sent a form for me to sign.
 

We also use the pattern for + object + infinitive in sentences after is or was.

The plan is for us to get to Barcelona by lunchtime.
The objective was for them to get the work finished by the end of last month.
 

We can add details to a noun by using the pattern for + object + infinitive

That is an expensive place for them to stay.
There is a lot of work for us to do.
There is no need for you to be so aggressive.
 

We also use the pattern for + object + infinitive after certain verbs and adjectives.

I am waiting for him to make the first move.
I have arranged for you to see the bank manager tomorrow morning.
We are keen for you to take the job.
I think it would be good for you to take a break now.

For 2
We can use for to mean ‘because’. We only use this in very formal English.

The divers have to be careful for a sudden change in conditions could be dangerous.
Read the instructions carefully for you will only get one chance to enter the information.
We can use for to talk about a purpose or a reason.

What did you that for?
What is that for?
Thank you for your letter.
I don’t have enough money for the ticket.
I need treatment for my bad back.
For can mean that you are in favour/favor of something.

He is for the idea of cutting taxes.
I am for this change in the way we do things.
You need to stand up for what is right.
We can use for with expressions of time and distance.

I walked for miles.
I waited for a long time.
We will be away for the next week.
Sometimes we can omit the for completely in these expressions without changing the meaning.

 I walked miles.
I waited a long time.
With the present perfect, for refers to a length of time. Since refers to the starting point.

I have studied English for seven years.
I have studied English since I was 12.
Here are some useful expressions using for

I enclose a cheque/check for 100 euros
What’s another word for stupid?
I’ve known him for ages.
I am all for making this change.
Get ready.  -What for?   -Anne is coming.