In which voice is "The book was read by the teacher" written?

The sentence "The book was read by the teacher" is written in passive voice because the subject of the sentence (the book) is being acted upon rather than performing the action. In passive voice constructions, the focus is on the recipient of the action rather than the doer. Here, the teacher is the one who performs the action of reading, but the sentence emphasizes the book being read. The structure of the sentence typically includes a form of the verb "to be" (in this case, "was") followed by the past participle of the main verb ("read"), which is a hallmark of passive construction. This deployment indicates that the sentence is highlighting the experience of the subject rather than the subject's action, reaffirming that it is indeed in the passive voice.