Today’s topic is a verb おわる. One of the four sounds a bit odd. Which one is it and why?
a. 映画が終わる/えいがが おわる
b. 宿題が終わる/しゅくだいが おわる
c. 読書が終わる/どくしょが おわる
d. 冬が終わる/ふゆが おわる
The answer is c. おわる is a intransitive verb which means [something] finishes/ends. Reading a book does not finish unless you finish it, so the odd one is c.
If I say that, then somebody might say what about homework? If you say that, I’m sure your teacher loves teaching you! If you work hard on your homework, you should say しゅくだいを おえる instead of しゅくだいが おわる. However, if your homework was to watch a video and if you halfheartedly watched it, you can say しゅくだいが おわる.
Going back to the original question, if you change 読書が終わる into 読書の時間が終わる（どくしょの じかんが おわる）, that is fine as the time for reading will come to an end whether or not you were actively reading.
