被 sentences (the passive)

When it's done TO you

• The passive: the subject receives the action. "The book was taken."
• Chinese marks it with (passive: by)被bèi (+ an optional doer).
• book书shū(passive: by)被bèihe / him他tāto take away拿走ná zǒu(completed / change)了le = "the book was taken (away) by him."

Subj + (passive: by)被bèi + (Doer) + Verb Phrase

• (passive: by)被bèi flags the subject as the one acted upon.

book书shūby被bèihim他tātake away拿走ná zǒu了le。

• book书shū(passive: by)被bèihe / him他tāto take away拿走ná zǒu(completed / change)了le = "the book was taken by him."

The doer is optional

• book书shū(passive: by)被bèito take away拿走ná zǒu(completed / change)了le (the book was taken) — drop he / him他tā if the doer is unknown.

Recap

Read the full reference: HSK 3 grammar — Sentence patterns.