Take a look at these two sentences. Which one is more commonly used?I was not capable of finishing the marathon.
I was not capable to finish the marathon.
Well done if you chose (1). This is an example of a phrase which uses preposition 'of' + gerund
(-ing). The second example uses an infinitive ('to...') and is not correct.
Compare, however:
I was not able to finish the marathon.
I lacked the stamina to finish the marathon.
I was not fit enough to finish the marathon.
Here in each case the infinitive is correct.
Gerund or infinitive? It is a tricky area of grammar, but one worth learning about.
Prepositions are often a sign that you need a gerund. There are many phrases in English using 'of', or other prespositions like 'for' or 'in', followed by a gerund. Here are some:
it's a question of, it's a matter of, instead of, beware of, in charge of, the point of
It's a question of getting our priorities right.
Instead of buying a house now, let's wait until spring.
Beware of getting your fingers caught in the door!
Who is in charge of buying the tickets?
What's the point of repeating what I have already said?
Note: Sometimes a phrase can take BOTH a gerund or an infinitive, but in different situations and with different prepositions. An example is 'have a chance'.
I had no chance of winning the race.
I hope I get a chance to say goodbye.
Note: Although the gerund is a noun, it is very common to use both possessive pronouns (like 'my') and direct personal pronouns (like 'me') before them. The possessive pronoun is more formal. For example, both these sentences would be OK, but the first one is more formal:
There is no question of my working next Sunday.
There is no question of me working next Sunday.
You could also rearrange this to put the gerund first: Working next Sunday is out of the question.
