の or を？ What is the correct answer and why is it correct?


This is a question that I have found in a JLPT-N5 mock test paper.

> 弟はへや＿＿＿そうじをしました。

And the answer for that is の, but I selected を. Could someone possibly clarify
this please? Why の and why not を? What is wrong if one puts を there?




You cannot have two を in a single clause. The structure [Noun]を[Verb] can be
realised as:

  1. **へや** をそうじする
  2. **へやのそうじ** をする

Where in そうじする is the verb in 1, and する is the verb in 2

Also note that in 2, そうじ is syntactically a noun and へやのそうじ is syntactically a
noun, as opposed to そうじする which is a verb in 1.

See also these:

  * Related Answer: [snailplane explaning that you cannot have two を in a single clause](https://japanese.stackexchange.com/a/16289/542)

  * Related Question: [Can we optionally include (or exclude) an を particle in between the noun of the する-verb and the する itself?](https://japanese.stackexchange.com/q/1532/542)

  * Related Question: [How do I add an object to noun を します verbs?](https://japanese.stackexchange.com/q/4076/542)

  * Related Question: [Difference between [Noun]する vs [Noun]をする vs [Noun]だ](https://japanese.stackexchange.com/q/29519/542)




You cannot have two を in a single clause. The structure [Noun]を[Verb] can be
realised as:

  1. **へや** をそうじする
  2. **へやのそうじ** をする

Where in そうじする is the verb in 1, and する is the verb in 2

Also note that in 2, そうじ is syntactically a noun and へやのそうじ is syntactically a
noun, as opposed to そうじする which is a verb in 1.

See also these:

  * Related Answer: [snailplane explaning that you cannot have two を in a single clause](https://japanese.stackexchange.com/a/16289/542)

  * Related Question: [Can we optionally include (or exclude) an を particle in between the noun of the する-verb and the する itself?](https://japanese.stackexchange.com/q/1532/542)

  * Related Question: [How do I add an object to noun を します verbs?](https://japanese.stackexchange.com/q/4076/542)

  * Related Question: [Difference between [Noun]する vs [Noun]をする vs [Noun]だ](https://japanese.stackexchange.com/q/29519/542)

