Use of "to" as a preposition

I have many doubts about this cases (all of them were extracted from books, web pages and so on):

  1. 3 steps [color=red]to losing weight

  2. The key [color=red]to understanding Islam

  3. The secret [color=red]to making money online

  4. The Secret [color=red]to Success :cry: (why there’s no “ing” like in the previous sentence)

  5. 3 steps [color=red]to lose weight
    The requirements [color=red]to gain entrance . . .

I do not know why it is followed the termination “ing” after “to” when it is used the article “the” at the beggining, but in other cases not :shock: even with the same noun after “the” such as “secret” (cases 3 and 4)

Help me out with this too please!
6. We’re going to look at a number of approaches [color=red]to describing the diferrences . . .
7. From playing with sibblings [color=red]to negotiating allowances

Thanks in advance!

This is a complicated subject. All the -ing forms in your examples are gerunds. There are three general observations I can make.

  • A gerund is a sort of noun; a verb that can have a direct object or the object of a preposition can usually also have a gerund instead of a noun.
  • Some verbs regularly go with gerunds, others with infinitives (and some can go with either): there is no real rule for this; you’ll have to learn which goes with what by practice, or from a dictionary.
  • The mistake of using the infinitive where only the gerund is right is often made, but the reverse mistake is not so frequent; when in doubt, I’d go for a gerund.

The sentences you gave are special, since their verbs all have to + gerund. This “to” is here not the infinitive particle, but a regular preposition. In other words: the gerund could in each case be replaced with a noun, as in “three steps to weight loss” or “the key to knowledge of Islam”; the gerund just behaves like any other noun.