Be Alarmed To Do vs. Alarmed At Something distinguishes two directly documented complement patterns for the adjective “alarmed.” Use alarmed + to-infinitive for the directly documented infinitival construction; use alarmed at + noun phrase for the separately documented prepositional construction. The page stays within those attested patterns and does not infer a broader rule from synonymy.
ReviewedEvidence1 sourceSectionEnglish Usage
Quick answer
Use alarmed + to-infinitive when the adjective takes its documented infinitive complement; use alarmed at + noun phrase when the complement is introduced by the documented preposition.
Key details
Confusion Familyadjective-complement
Rule Familyadjective complementation
Termsalarmed + to-infinitive, alarmed at + noun phrase
Choose the right form
Decision table for Be Alarmed To Do vs. Alarmed At Something
Complement
Pattern
Use
reaction linked to infinitive event
alarmed + to-infinitive
alarmed to discover ...
cause/thing of alarm
alarmed at + noun/clause-like complement
alarmed at the increase
Quick tests
Cause-versus-event test
Are you presenting the event that triggered the reaction with an infinitive, or naming the alarming thing after a preposition?
If yes: Use “alarmed to + verb” for the documented infinitive construction.
If no: Use “alarmed at + complement” when naming the thing, fact, or circumstance causing alarm.
Caveat: Keep the distinction at the level supported by the reviewed complement patterns; do not infer that synonyms behave identically.
Examples
Example
We were alarmed to discover the error.
The infinitive presents the event that prompted alarm.
Example
We were alarmed at the sudden drop.
The noun phrase names the circumstance causing alarm.
Example
Both patterns are standard when their complement roles fit the sentence.
The choice is constructional, not a simple one-form-only rule.
Further guidance
Core difference
Use alarmed + to-infinitive for the directly documented infinitival construction; use alarmed at + noun phrase for the separately documented prepositional construction.
Style Boundary
Treat this as a comparison of directly documented complement patterns, not as a claim that every other complement is impossible. Choose the construction that matches the intended grammatical relationship.
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.
Be Afraid To Do vs. Afraid Of Something distinguishes two directly documented complement patterns for the adjective “afraid.” Use afraid + to-infinitive for the directly documented infinitival construction; use afraid of + noun phrase for the separately documented prepositional construction. The page stays within those attested patterns and does not infer a broader rule from synonymy.
Be Amused To Do vs. Amused By Something distinguishes two directly documented complement patterns for the adjective “amused.” Use amused + to-infinitive for the directly documented infinitival construction; use amused by + noun phrase for the separately documented prepositional construction. The guide stays within those attested patterns and does not infer a broader rule from synonymy.
Be Annoyed To Do vs. Annoyed About Something distinguishes two directly documented complement patterns for the adjective “annoyed.” Use annoyed + to-infinitive for the directly documented infinitival construction; use annoyed about + noun phrase for the separately documented prepositional construction. The page stays within those attested patterns and does not infer a broader rule from synonymy.
Be Astonished To Do vs. Astonished At Something distinguishes two directly documented complement patterns for the adjective “astonished.” Use astonished + to-infinitive for the directly documented infinitival construction; use astonished at + noun phrase for the separately documented prepositional construction. The page stays within those attested patterns and does not infer a broader rule from synonymy.
Be Astounded To Do vs. Astounded By Something distinguishes two directly documented complement patterns for the adjective “astounded.” Use astounded + to-infinitive for the directly documented infinitival construction; use astounded at/by + noun phrase for the separately documented prepositional construction. The guide stays within those attested patterns and does not infer a broader rule from synonymy.
Be Concerned To Do vs. Concerned About Something distinguishes two directly documented complement patterns for the adjective “concerned.” Use concerned + to-infinitive for the directly documented infinitival construction; use concerned about + noun phrase for the separately documented prepositional construction. The page stays within those attested patterns and does not infer a broader rule from synonymy.
