“Allow” can take an activity as its object, as in “allow smoking,” or a person/thing followed by a to-infinitive, as in “allow visitors to enter.” The patterns answer different structural questions: what is allowed versus who is allowed to do what.
ReviewedEvidence1 sourceSectionEnglish Usage
Quick answer
Use “allow + activity/-ing” when what is permitted is the activity itself, and “allow + person + to-infinitive” when you name who receives permission.
Key details
Confusion Familygrammar-and-usage distinction
Rule Familyverb complement pattern
Termsallow doing, allow someone to do
Further guidance
Activity Pattern
Use allow + an activity or -ing form when the permitted thing is the activity itself, such as allowing smoking or parking.
Boundary
Do not drop the object from the object + to-infinitive pattern and write bare “allow to do” for the permission sense; either name the activity or name who is allowed to act.
Person Pattern
Use allow + person/thing + to-infinitive when you identify the person or thing that is permitted or enabled to act.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
Cambridge documents both admit + -ing and admit to + -ing for acknowledging something. Other passive patterns such as “be admitted to be” are separate constructions.
Both patterns are standard. “Advise waiting” recommends an action generally or in context, while “advise him to wait” names the person who is advised to perform it. A that-clause is another standard option.
When “afford” is followed directly by another verb, standard learner references use a to-infinitive: “afford to do.” An -ing form can appear elsewhere in a sentence, but it is not a like-for-like direct complement after “afford.”
“Agree to do” expresses consent to take an action. An -ing form normally follows a preposition in patterns such as “agree with doing,” which expresses approval rather than the direct promise-to-act construction.
Cambridge documents aim + to-infinitive for intention and aim at for directing effort toward an objective. Do not omit the preposition and present bare “aim doing” as equivalent to “aim to do.”
Cambridge describes appear as a linking verb and with a to-infinitive; a progressive action can sit inside that infinitive, as in “appears to be working.” An -ing form after appear can belong to another structure or sense, so “appear doing” is not a free alternative to “appear to do.”
