Verbals in Idioms: Infinitives and Gerunds

A common source of confusion for English speakers is the idiomatic distinction between infinitives (verb forms with to) and gerunds (“-ing verbs” acting as nouns). Some expressions arbitrarily require an infinitive; other expressions arbitrarily require a gerund. In the latter case, gerunds often follow the preposition of.

able of solving the problem
able to solve the problem

capable to solve the problem
capable of solving the problem

Some expressions can be used with either form:

continue going to that store
continue to go to that store

Some of the entries on this Common Errors in Usage list have to do with idiomatic verbals, such as “be sure + [infinitive]” and “can’t help + [gerund].” Unfortunately, these expressions generally must be memorized individually. But recognizing this pattern, this feature of English, will help you notice and pay closer attention to all of those individual cases.