There is one very simple rule about prepositions. And, unlike most rules, this rule has no exceptions.
A preposition is followed by a “noun”. It is never followed by a verb.
By “noun” we include:
- noun (dog, money, love)
- proper noun (name) (Bangkok, Mary)
- pronoun (you, him, us)
- noun group (my first job)
- gerund (swimming)
A preposition cannot be followed by a verb. If we want to follow a preposition by a verb, we must use the “-ing” form which is really a gerund or verb in noun form.
- I would like to go now.
- She used to smoke.
The answer is that in “I would like to go now” and “She used to smoke”, the word “to” is not a preposition. It is part of the infinitive (“to go”, “to smoke”).
Here are some examples:
|subject + verb||preposition||“noun”||note|
|The food is||on||the table.||noun|
|She lives||in||Japan.||proper noun|
|Tara is looking||for||you.||pronoun|
|The letter is||under||your blue book.||noun group|
|Pascal is used||to||English people.|
|She isn’t used||to||working.||gerund|