To (+ ~ing)
When using to as a preposition, it can be used together with the ~ing form (present participle) of verbs. ex. I’m looking forward to seeing you tomorrow.
This structure is most commonly used with verb clauses such as: look forward to; object to; be used to; prefer (doing something) to; get around to; in addition to
Place to after one of the verb clauses above and in front of the ~ing form (present participle) of the verb.
To + present participle
Ex. I am used to working on the weekends.
Present participles are formed depending on the spelling of the verb:
1. Most verbs: + ing: work > working
2. Verbs ending in ~e: (-)e + ing >> make > making
3. Verbs ending in ~ie: (-)ie + ying: lie > lying Doubling (ex. stopping)
4. 1 vowel + 1 consonant > double consonant*: stop > stopping; run > running
5. 2 vowels > don’t double: sleep > sleeping
6. 2 consonants > don’t double: want > wanting
*Only double stressed syllables: begin > beginning (double); happen > happening (single)
Be careful about the word to. To is really two words.
One use of to is as a infinitive marker (ex. to swim).
The other use is as a preposition.
The preposition use of to can be used with present participles, but the infinitive marker can not.