First of all, a quick reminder of what we mean by the passive.
Present
Passive
to approve
to be approved
to say
to be told
To create the passive in Japanese, the rules depend on the verb group:
Group 1 (u-verbs): Change the final u vowel to an a vowel and add れる. (Exception: Verbs ending in the vowel う change to わ instead of あ, e.g. 買う becomes 買われる).
Grammatically, the subject performing the action is followed by に, which we can think of as meaning “by”. For certain verbs there is no true direct passive (e.g. “to go” and “to come”), but we will see the passive conjugation used for other purposes later.
私は評価する。
I will evaluate.
私は評価される。
I will be evaluated.
私は先生に評価される。
I will be evaluated by the teacher.
蚊が私を刺した。
A mosquito bit me.
私は蚊に刺された。
I was bitten by a mosquito.
お母さんが私に怒った。
My mother got angry at me.
私はお母さんに怒られた。
I was yelled at by my mother.
レビューが素晴らしいと褒められて嬉しい。
I was happy to be praised that my review was excellent.
新しいシステムを導入する。
Install a new system.
新しいシステムが導入される。
A new system will be installed.
蒸気エンジンが発明される前に馬で旅をするのは一番早い方法だった。
Before the steam engine was invented, travelling by horse was the quickest way.
今朝はエレベーターが急に止まって、1時間も閉じ込められていました。
This morning the elevator suddenly stopped and I was trapped for one hour.
The “Suffering” Passive (Adversative Passive)
A crucial concept for the JLPT is the “suffering passive” (迷惑の受身). Unlike English, Japanese allows intransitive verbs (verbs without a direct object) to be put into the passive voice. This is used specifically to express that the speaker was negatively affected or inconvenienced by someone else’s action.
雨に降られて、服が濡れてしまった。
I got rained on (I suffered the rain falling), and my clothes got wet.
夜中に赤ちゃんに泣かれて、全然寝られなかった。
The baby cried in the middle of the night (affecting me), so I couldn’t sleep at all.
Group 2 Ambiguity
For Group 2 verbs this does represent one potential issue; namely, without context the following conjugation can mean one of two things (Passive or Potential).
私は食べられる。
I can eat.
私は食べられる。
I will be eaten.
But as soon as we add another word and a particle, it becomes clear which we mean.
私は納豆が食べられる。
I can eat natto.
私は熊に食べられる。
I will be eaten by a bear.
その話は広く知られています。
That story is widely known.
機会を与えられたら絶対無駄にしないよ。
If I’m given a chance I definitely won’t waste it.