The use of 'to' as an infinitive and preposition

In my earlier post, 'to' is used as an infinitive. For example, 'to' in the following sentence is an infinitive:

He came to visit me when I was ill.

I am going to discuss the use of 'to' as a preposition in this post.

As I mentioned in my post very much earlier, a preposition can be followed by a noun/noun phrase, a pronoun or an ing-verb. The examples below should make this point clear:

Example 1

My grandmother looks after my sister when my mother is at work.

['my sister' behind the preposition 'after' is a noun phrase and 'work' after the preposition ‘at’ is a noun.]

Example 2

The police are still after him.

[The pronoun 'him' is used after the preposition 'after']

Example 3

They kept on trying until they succeeded.

[The word after the preposition 'on' is an ing-verb or a gerund.]

Now look at how 'to' is used as a preposition through the following examples:

Example 1

Diligence is the key to success.

[The noun 'success' is used after 'to'.]

Example 2

The extortionist resorted to force when his victim refused to part with his money.
[It is another case of a noun after a preposition.]

Example 3

They talked to her to calm her.

[The pronoun 'her' is used after 'to' which is used as a preposition here.]

Example 4

I look forward to receiving your letter soon.

[The word after 'to' is an ing-verb.]

Example 5

We resorted to using river water as our drink to quench our thirst.

[Another example of using an ing-verb after a preposition.]