"She opened the door" and "The door opened" both use the exact same verb, unchanged, with no "be" and no passive structure, yet the object of the first sentence becomes the subject of the second. This is a genuinely advanced, easy-to-miss pattern called the ergative verb, and getting comfortable with it makes descriptions of events sound significantly more natural and less over-explained.
2. Quick Summary
⚡ Ergative Verbs at a Glance
Transitive UseShe opened the door. (someone acts on an object)
Ergative UseThe door opened. (same verb, object becomes subject, no agent stated)
Not PassiveNo "be" + past participle, this is active voice
Common Mistake"The door was opened by itself" instead of "the door opened"
3. How Ergative Verbs Work
Transitive (with agent)
Ergative (object becomes subject)
He broke the window.
The window broke.
I boiled the water.
The water boiled.
She changed her plans.
Her plans changed.
They increased the price.
The price increased.
💡
The quick test
If you can move the object of a sentence into subject position, keep the same verb form, and drop the original subject entirely, without adding "be", you're likely dealing with an ergative verb.
4. Common Ergative Verbs
Verb
Example
open / close
The shop opens at nine. The door closed suddenly.
break
The glass broke when it fell.
start / stop
The engine started. The rain stopped.
change
The weather changed quickly.
increase / decrease
Sales increased last quarter.
improve
Her English improved a lot.
cook / burn
The rice is cooking. The toast burned.
5. The "Middle Voice" Use
A related, slightly different pattern uses an ergative-style structure to describe a general property of something, not a single event, often with an adverb.
Sentence
Meaning
This book sells well.
People generally buy this book easily, a property of the book, not a single sale.
This fabric washes easily.
The fabric is generally easy to wash, a general characteristic.
The door doesn't open smoothly.
Describes how the door generally behaves, not one specific instance.
6. Common Mistakes
❌ Incorrect
✅ Correct
Why
The door was opened by itself.
The door opened.
Ergative verbs already express this meaning; adding passive "be" is redundant and unnatural.
The water was boiled by three minutes.
The water boiled for three minutes.
Unnecessary passive; the ergative form is simpler and more natural here.
The price was increased itself.
The price increased.
"Itself" is unnecessary and unnatural, the ergative verb already implies no external agent is named.
7. Exercises
A. Gap Fill — Rewrite using the ergative form (8 questions)
1. She opened the window. → The window ___.
2. He broke the vase. → The vase ___.
3. I boiled the soup. → The soup ___.
4. They increased the rent. → The rent ___.
5. She started the car. → The car ___.
6. He changed his mind. → His mind ___.
7. The chef burned the toast. → The toast ___.
8. Her English improved a lot. (already ergative, identify the subject)
Show Answers (A)
1. opened 2. broke 3. boiled 4. increased 5. started 6. changed 7. burned 8. "Her English" is the subject
B. Multiple Choice (5 questions)
1. The door ___. (a) opened (b) was opened by itself
2. This book ___ well. (a) sells (b) is sold
3. The glass ___ when it fell. (a) broke (b) was broken by itself
4. Prices ___ last year. (a) increased (b) were increased themselves
5. The rain ___ suddenly. (a) stopped (b) was stopped
Show Answers (B)
1.a 2.a 3.a 4.a 5.a
C. Error Correction (4 questions)
1. The door was opened by itself.
2. The water was boiled by three minutes.
3. The price was increased itself.
4. The engine was started by pressing the button, it started.
Show Answers (C)
1. The door opened. 2. The water boiled for three minutes. 3. The price increased. 4. The engine started when the button was pressed.
D. Freer Practice — Write Your Own Sentences (2 tasks)
1. Write a sentence using an ergative verb describing something that changed on its own.
2. Write a "middle voice" sentence describing a general property (e.g. "this... sells/washes/opens...").
Show Answers (D)
Model answers will vary. Examples: 1. "The milk went off because I forgot to put it in the fridge." 2. "This fabric irons easily."
8. Mini Quiz
9. Exam Focus — Cambridge, IELTS, SELT
Exam
How This Is Tested
Sample Question
Cambridge C1 Advanced / C2 Proficiency
Natural use of ergative verbs, avoiding over-explained passive constructions, is a marker of high-level control in Writing and Use of English.
Identifying and correcting an unnecessary passive: "the door was opened by itself" → "the door opened."
IELTS Writing Task 1
Describing trends and changes (prices increased, sales dropped) relies heavily on ergative verbs.
"Unemployment decreased steadily between 2020 and 2024."
Trinity ISE III/IV (higher SELT levels)
Natural descriptions of everyday events (the milk went off, the car broke down) reflect genuine fluency at advanced levels.
"My car broke down on the way here" used naturally in conversation.
10. Frequently Asked Questions
A verb that can be used transitively (with an object doing the action to something) or intransitively (with the same noun as subject, the action just happening), without changing form: "She opened the door" and "The door opened."
Passive voice needs "be" plus a past participle: "the door was opened." "The door opened" is active voice, past simple, it just doesn't state who opened it, because the verb itself allows the object to become the subject directly.
Adding an unnecessary passive structure: "the door was opened by itself" instead of the natural "the door opened." Ergative verbs already express this meaning without "be."
No — most verbs are strictly transitive or strictly intransitive. Ergative verbs are a specific, limited set, often involving physical changes of state (breaking, opening, cooking) or market behaviour (selling, changing in price).
A special case where the subject isn't the person doing the action, but the sentence still describes a general property: "This book sells well" doesn't mean the book is selling itself, it describes how easily people buy it.
At higher levels, natural use of common ergative verbs (the milk went off, the car broke down) adds genuine fluency to descriptions of everyday events.
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