Context is the main factor determining whether a to-infinitive or a gerund should be used in the verbal complement after a verb. Bara, Bosco, Bucciarleili (2004) mentioned context could be divided into six categories: access, space, time, discourse, behavioral move, and status. According to Sayer (2007), time and discourse contribute to the choice of to-infinitive or a gerund. Time refers to the sequence of a series of actions done by the agent, and discourse refers to things mentioned by the speaker previously.
Some verbs can be followed by to-infinitive only. For example, want, wish, expect, agree, prepare, promise. Baratta-Zborowski (1998) stated that Bolinger mentioned infinitives are used in events that are "hypothetical, future, unfulfilled."
The following are the example sentences using to-infinitive in verbal complement:
1. I want to eat a hamburger.
2. I wish to see you again soon.
3. I prepare to sing a song.
4. I promise to finish it as soon as possible.
All the actions in the verbal complement are referred to the action that is not yet done by the agent, i.e., future action. The time of the verb in verbal complement always happens after the time of the main verb of the same sentence.
Some verbs can be followed by gerunds only. For example, finish, enjoy, miss, celebrate, recognize, keep, admit. Baratta-Zborowski (1998) stated that Bolinger mentioned gerunds are used in events that are "real, vivid, fulfilled."
The following are example sentences using gerund in verbal complement:
5. I enjoy playing basketball.
6. I finish cleaning my room.
7. I keep eating hamburgers.
8. I admit stealing the diamond.
All the actions in the verbal complement are referred to the action that has been already performed by the agent, i.e., past action or the action that is still ongoing. The time of the verb in verbal complement always happens before the time of the main verb of the same sentence. This also applies to verbs such as enjoy and keep as they have to do the action before they enjoy or keep doing the same action.
Some verbs can be followed by both to-infinitive and gerund. For example, remember, forget, stop, quit, regret, like.
9a. I remember to do my homework.
b. I remember doing my homework.
10a. I stopped to smoke.
b. I stopped smoking.
There is a semantic difference in using to-infinitive and gerund. Hence, context determines whether a to-infinitive or a gerund is used. 9a carries the meaning of "I haven't done my homework, and I will finish it," while 9b carries the meaning of "I have done my homework, and I remember it." 10a carries the meaning of "I stopped what I was doing at that moment and then I went to smoke," while 10b carries the meaning of "I haven't smoked for a while." Therefore, the choice of whether a to-infinitive or a gerund is used is unclear unless we know about the context.
Apart from context, syntactic rules also determine whether gerunds or infinitives should be used after verbs. In sentences that include a prepositional phrase following a verb phrase and modifying the verb, only gerunds can be used after the prepositions in the prepositional phrase as gerunds can follow a preposition but infinitives cannot (Johnston, n.d.). For example, in sentences “She won the competition by performing excellently.” and “He was sued for murdering.” Only gerunds can be used after the prepositions but infinitives cannot. However, in some sentence structures, an infinitive should be used instead of a gerund after a verb. There is a sentence structure that some verbs are followed by a pronoun or noun referring to a person, and then an infinitive (Johnston, n.d.). For example, “He encouraged her to read the book.” and “She told the band to start the show.” In this sentence structure, only infinitives can be used in this position but gerunds cannot. Therefore, the use of gerunds and infinitives after verbs can also be determined by the syntactic rules in English.