knock
knock — noun
1. a short, sharp sound produced when a hand or object hits a hard surface, especia
a short, sharp sound produced when a hand or object hits a hard surface, especially a door or window, often to get someone's attention
Élise heard a knock at the door and went to answer it.
knock at the door — common pattern for entry
There was a loud knock on the classroom window, and everyone turned to look.
A soft knock came from the bedroom, but nobody was inside.
The postman gave three quick knocks before leaving a package by the door.
文法句型
a knock + at/on + [door/window]
用法筆記
Countable noun, usually singular when referring to a single incident. Often preceded by a possessive form of the person who hears it (e.g., 'I heard a knock'; 'She was woken by a knock').
常見錯誤
2. a hard hit from an object or person that lands on a body part or surface, often
a hard hit from an object or person that lands on a body part or surface, often causing pain or damage
The knock on his knee left a purple bruise that lasted for a week.
knock on + body part for impact location
Beatriz took a hard knock to the shoulder when she slipped on the wet floor.
take a knock — collocation for receiving a hit
The wooden table had several knocks and scratches from years of use.
Vivek got a nasty knock on the head when the ladder fell sideways.
文法句型
a knock + to/on + [body part]
用法筆記
Countable noun. Often used with 'take a knock' (receive a blow) or 'get a knock' (suffer a blow). Not used for deliberate violent attacks such as punches in a fight — 'punch' or 'blow' would be more natural there.
常見錯誤
3. unkind or unfair critical remarks about a person, idea, or thing
unkind or unfair critical remarks about a person, idea, or thing
The biggest knock against the new café is that the coffee is too expensive.
the biggest knock against — common critical framing
Sivan accepted the knocks from the audience and used them to improve her presentation.
One common knock on the proposal is that it does not address safety concerns.
The mayor has taken plenty of knocks from the press over the new policy.
- praise
expression of approval, the opposite of criticism
文法句型
a/the knock + against + [person/thing]
用法筆記
Countable noun, found mostly in informal contexts such as journalism, reviews, and everyday conversation. Often appears in the structure 'the knock against [something] is [criticism]'.
常見錯誤
4. a negative event that damages someone's confidence, hopes, plans, or wellbeing
a negative event that damages someone's confidence, hopes, plans, or wellbeing
Losing her job was a serious knock to Valentina's confidence.
knock to confidence — metaphor for emotional setback
The team's early defeat was a huge knock to their championship hopes.
Small businesses suffered a severe knock when the local factory closed down.
Failing the exam was a knock, but Wren studied harder and passed the next time.
- boost
something that lifts confidence or spirits
文法句型
a knock + to + [emotion/confidence/plans]
用法筆記
Countable noun, almost always singular. The pattern 'a knock to [abstract noun]' is very common. Stronger than 'disappointment' — implies actual damage or loss rather than simply feeling let down.
常見錯誤
knock — verb
1. to strike a hard surface such as a door or window with your hand or an object, e
to strike a hard surface such as a door or window with your hand or an object, especially to get someone's attention or announce your presence
Élise knocked on the office door before stepping inside.
knock on + door — most common intransitive pattern
A delivery driver was knocking loudly at the front gate, but nobody heard.
Takeshi knocked three times and then pushed the door open slowly.
The teacher knocked her pen against the desk to get the class's attention.
文法句型
knock + on/at + [door/window]
knock + [object] + on + [surface]
用法筆記
When used intransitively, the preposition is 'on' (American and British) or 'at' (more common in British English for doors). When transitive, the object is the thing you strike the surface with, not the surface itself (e.g., 'knock your fist on the table', not 'knock the table').
常見錯誤
2. If an engine knocks, it produces a repeated metallic tapping sound caused by imp
If an engine knocks, it produces a repeated metallic tapping sound caused by improper fuel burning or a faulty component.
The old truck's engine started knocking after Mert filled it with cheap fuel.
engine started knocking — common verb + start pattern
Valentina heard the engine knocking on the highway and pulled over immediately.
A knocking engine often means the spark plugs need to be replaced soon.
If your engine knocks, take it to a mechanic before the damage gets worse.
文法句型
[engine] + knocks
[engine] + is knocking
用法筆記
Intransitive only — the subject is always the engine or vehicle. The technical term for this condition is 'engine detonation' or 'engine pinging'. Not used metaphorically (you cannot say 'my stomach is knocking' to mean growling).
常見錯誤
3. to make repeated tapping or banging sounds inside a building's pipes, radiator,
to make repeated tapping or banging sounds inside a building's pipes, radiator, or heating system, often due to temperature changes, trapped air, or water pressure
The pipes in the bathroom knock every time someone turns on the hot water.
pipes knock — subject + intransitive verb pattern
Sofie called the plumber because the radiator was knocking all night.
The heating system knocks loudly when it first turns on in the morning.
Old houses often have knocking pipes that need to be fixed by a professional.
文法句型
[pipe/radiator/heating] + knocks
用法筆記
Intransitive only. The typical problem is called 'water hammer' in plumbing. Distinguished from verb sense 2 (engine noise) by the subject: pipes/radiators vs. engines. Common in home-maintenance discussions.
常見錯誤
4. to strike someone or something with enough force to make them move, fall, leave
to strike someone or something with enough force to make them move, fall, leave a position, or enter a different state
Christopher accidentally knocked the glass off the table with his elbow.
knock + object + off + surface — direction pattern
The strong wind knocked several flower pots off the balcony railing.
Femi knocked the ball across the field during the final minute of the game.
A cyclist came around the corner and nearly knocked the old woman over.
The toddler knocked a whole stack of picture books off the library shelf.
文法句型
knock + [object] + [adverb/preposition]
knock + [object] + off/over/down/into + [target]
用法筆記
Transitive verb with an object (the person/thing hit) and typically a directional adverb or prepositional phrase (off, over, down, into, across). The direction component is almost always required — 'I knocked the cup' is incomplete; 'I knocked the cup off the table' is correct.
常見錯誤
5. to remove a wall that separates two rooms, usually to create one larger living s
to remove a wall that separates two rooms, usually to create one larger living space
The Watanabes decided to knock the wall between the kitchen and the dining room.
knock + the wall between [room] and [room]
The Watanabes paid a builder to knock through from the living room into the study.
If you knock down the dividing wall, the ground floor will feel much more spacious.
The couple knocked two small bedrooms into one large master bedroom.
- build
to construct a wall, the opposite of removing one
文法句型
knock + [wall] + down/through
knock through + [prepositional phrase]
用法筆記
Often used as a phrasal verb 'knock through' (remove part of a wall to connect rooms) or 'knock down' (completely demolish a wall). Not used for removing external walls (that is 'demolish').
常見錯誤
6. to say unkind or unfair things about someone or something, often in a repeated o
to say unkind or unfair things about someone or something, often in a repeated or habitual way
Critics knocked the film for its weak storyline, but audiences loved it anyway.
knock + [something] + for + [reason] — criticism pattern
Mert's colleagues are always knocking his ideas without offering better ones.
Diya knocked the city's bike lane plan at the town hall meeting, but the mayor defended it.
Stop knocking yourself all the time — you did an excellent job on the project.
- praise
to express warm approval or admiration
- compliment
to politely express praise
文法句型
knock + [person/thing]
always + knocking + [person/thing]
用法筆記
Informal verb, more common in spoken English and journalism than in formal writing. Often conveys that the criticism is unfair or excessive. The reflexive form 'knock yourself' (criticize yourself) is very common in spoken encouragement.