ing

[learner.]

I'm here to apply for the job.
I'm here to applying for the job.
Which is the correct sentence?
When can we add (ing)after (to) ?
Thanks..

[5jj]

I'm here to apply for the job.
I'm here to applying for the job.X

When can we add (ing)after (to) ?

When 'to' is a preposition rather than part of the to-infinitive, an ing-form (gerund) may be possible.

I look forward to seeing you.
I am used to driving in Prague.
I prefer drivimg to going by coach.
I went from eating too much to drinking too much.

Note that in these examples,a to-infinitive is not possible, but a noun is, for example:

I look forward to the party.
I am used to Prague traffic.
I prefer cars to coaches.
I went from over-indulgence in food to alcoholism.

In your example, neither a gerund nor a noun is possible:

I'm here to applying for the job.X
I am here to the job/application.X

[learner.]

How do we know that 'to' is a preposition rather than part of the to-infinitive, ?
if i say (I`m here applying for the job)Is it right?

[Soup]

How do we know that 'to' is a preposition rather than part of the to-infinitive, ?
if i say (I`m here applying for the job)Is it right?

Test it by adding the words 'something' for nouns and 'do something' for verbs:

Noun: I am used to <(doing) something>; e.g., sleeping, Prague traffic
Verb: I am going to <do something>; e.g., sleep, walk

_______________

Be + ing: I am applying for the job. / I am here applying for the job.

[learner.]

when we finish drinking our coffe,we`ll probably go home.
why we don`t say ;when we finish to drink our coffe,we`ll probably go home.

[bhaisahab]

When we finish drinking our coffee, we`ll probably go home.
Why don't we say; "when we finish to drink our coffee, we`ll probably go home"?

"Finish" is always followed by a gerund.