Learn Hardcore Japanese: pasokon ha sensei ni naosaremasita. - The computer was repaired by the teacher.

直されました is the polite past passive form of 直す (“to fix”). In Japanese, passive voice is formed (for godan verbs like 直す) by replacing -す with -される and then adding the polite ending -ました. Using the passive shifts focus onto the computer as the thing affected by the repair, rather than on the person doing the repairing.

Why is the particle に used after 先生 instead of が or は?

In passive sentences, the doer (agent) of the action is marked with に. So 先生に直されました literally means “was repaired by the teacher.” Using が would make the teacher the grammatical subject, which is not how agents are marked in Japanese passives.

Why is パソコン marked with は instead of が?

Although the computer is the “subject” of the passive, learners often use は to mark the topic when they want to contrast or emphasize it. Here パソコンは highlights “as for the computer,” it was repaired. You could also say パソコンが先生に直されました, but は adds a topical nuance.

Why is there no direct-object marker を in this sentence?

In an active sentence (“Someone repaired the computer”), you would use を: 先生がパソコンを直しました. In the passive, that original object (パソコン) becomes the subject/topic (marked by が or は), and the agent takes に. Therefore, no を is needed.

Can I say パソコンは先生に修理されました instead of 直されました? What’s the difference?

Yes, 修理されました is also correct. 修理する is more technical/formal (“to repair”), while 直す is a bit more casual and can also mean “to correct” in other contexts. Both mean “to fix,” but choose 修理 for machines and formal contexts.

What’s the difference between 先生が直しました and 先生に直されました?

先生が直しました (active): “The teacher fixed (it).” Focus is on who did the action.
先生に直されました (passive): “It was fixed by the teacher.” Focus is on the computer being affected by the action.

Could I use パソコンは先生に直してもらいました instead?

Yes. 直してもらいました expresses that you received a favor; it means “I got the teacher to fix the computer.” The passive (直されました) simply reports that the computer got fixed, without emphasizing that it was done as a favor to you.

Is 直されました an instance of the “suffering passive” (迷惑の受身)?

No. A “suffering passive” implies the subject suffers some inconvenience or negative result (e.g., “I was forced to do something”). Here, 直されました is a neutral passive describing a change of state—the computer was repaired—without any connotation of inconvenience.