In English, the more common structure of an infinitive is [to] + [base verb form]. There are infinitives that appear with out the [to] in some cases.Originally Posted by guest
When one encounters [to] + ["ing" verb form] it is much different from an infinitive. The "ing" form is a present participle of a verb or a gerund.
In most cases, when one encounters [to] + ["ing verb], the [to] is a preposition or it is part of a phrasal verb that ends in [to], called either a preposition or a particle.
I look forward to seeing you.
[I] [look forward to] [seeing] [you].
subject - phrasal verb - gerund acting as verb direct object - object of gerund.
John was reading a guide to running marathons.
[John] [was reading] [a guide] [to] [running] marathons]
subject - verb - verb direct object - preposition - gerund acting as the object of the preposition - object of the gerund.
[to] + [be] + [past participle]
This is the structure of a passive infinitive. In English, the passive voice changes a sentence such that the subject is the recipient of the action, not the doer of the action.
John painted the fence. [John is the subject and he did the action.]
The fence was painted by John. [John still did the action, but "fence" is the subject.]
The infinitive form of the second verb would be "to be painted".
This infinitive can be used in a sentence where an infinitive could be used.
John was waiting for his car to be painted.
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