Why do we use a continuous verb after "adjective + of",

e.g. "I am capable of running 10k"

or "I am scared of sleeping in the dark"?

When we use "to" instead we do not, e.g. "I am scared to sleep in the dark"-- why is there a change from continuous to present for the verb?

  • These '-ing' words are not the continuous tense (as in I am running), but the gerund/participle, as James explains in his answer. Apr 15, 2022 at 7:07

1 Answer 1


"of" is a preposition, and generally the complement of a preposition can be either a noun phrase, a content clause or a participle-gerund.

In these cases it is idiomatic to use a participle-gerund. The gerund form is "running". It would not be correct to have an unmarked finite clause, or a finite predicate, as the object of a preposition. It would be incorrect to say *"I am capable of run 10k" It is also generally incorrect to say *"I am capable of run to 10k"

  • I think you meant "preposition" instead of "pronoun". Am I then correct in assuming that the following sentences use "run 10K" and "run to 10K" as examples of "unmarked finite clauses"? Apr 15, 2022 at 0:49
  • Yes, preposition, thank-you.. A finite clause is something like "I run 10k".
    – James K
    Apr 15, 2022 at 5:36
  • OK, so then the examples in the last sentence do not demonstrate the issue mentioned in the previous sentence ("an unmarked finite clause as the object of a preposition"). Sorry, I was just a bit confused by that when I first read it. Apr 15, 2022 at 5:50
  • "run 10k" is a finite predicate, Is this edit better?
    – James K
    Apr 15, 2022 at 6:08
  • That makes more sense to me, thanks! (Sorry to quibble.) Apr 15, 2022 at 6:12

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