verbs+in

[egerol1]

Hello friends,

I have a question: Can we use the preposition "in" in this sentence?

I'm thinking in going back to my country

or should I say I'm thinking of going back to my country.

I think second one is better but can I also use "in"?

[freezeframe]

Using in there is incorrect.

"I'm thinking of going back to my country" is correct.

[egerol1]

but what if I say

my purpose in sending this document to you....

is it correct?

[Raymott]

but what if I say

my purpose in sending this document to you....

is it correct?

Yes, it's correct, but it has nothing to so with the question you asked.
'purpose' is a noun.
Of course you can have a verb + in, as in your topic: "I sleep in this bed."