Japanese has pairs of verbs where English has one. 開きます and 開けます both concern a door opening, but they say different things about who opened it.
This is one of the genuinely unfamiliar features of Japanese grammar, and it is examined at N4 and in JFT-Basic vocabulary questions.
The distinction
Transitive (他動詞) - somebody does it to something. Takes を.
わたしが ドアを あけます。- I open the door.
Intransitive (自動詞) - it happens by itself. Takes が.
ドアが あきます。- The door opens.
The common pairs
| Intransitive (it does) | Transitive (I do it) |
|---|---|
| あきます (opens) | あけます (open it) |
| しまります (closes) | しめます (close it) |
| つきます (turns on) | つけます (turn it on) |
| きえます (goes out) | けします (turn it off) |
| はいります (enters) | いれます (put in) |
| でます (comes out) | だします (take out) |
| なおります (is fixed) | なおします (fix it) |
| とまります (stops) | とめます (stop it) |
| こわれます (breaks) | こわします (break it) |
| おちます (falls) | おとします (drop it) |
| はじまります (begins) | はじめます (begin it) |
| おわります (ends) | おわらせます (finish it) |
There is no perfect rule for predicting which is which, but the tendency is useful: pairs ending -eる are often transitive, and pairs ending -aる are often intransitive.
Why it matters at work
Because it changes responsibility.
- きかいが こわれました - the machine broke (it failed)
- きかいを こわしました - I broke the machine
Both are honest sentences, and they are not the same report. The first describes a fault; the second admits causing it. Being able to say the right one is worth learning properly: your first month of Japanese at work.
The ている trap
With an intransitive verb, ています often describes a resulting state rather than an ongoing action:
- まどが あいて います。- The window is open. (not “is opening”)
- でんきが ついて います。- The light is on.
Compare the transitive: まどを あけて います - I am opening the window, in progress.
This distinction appears in reading questions, where the answer turns on whether a thing is in a state or somebody is acting on it.
How to learn them
In pairs, never singly, and always inside a sentence with the correct particle:
ドアが あきます。/ ドアを あけます。
The particle is the memory hook. Once が and を are attached to the right halves of the pair, the verbs stop being confusable - and particle practice pays off everywhere else too: Japanese particles.
Test them under time pressure with the free practice test, which explains why each wrong option was tempting.