Is there a way to tell which sentences or structures particle wa can replace particle wo for emphasis in?


I've been told that in the sentence,

> kare wa tsugou ga warui koto wa kakusu

wo can be used instead of wa in the last particle like,

> kare wa tsugou ga warui koto wo kakusu

but that wa is used instead of wo for emphasis. I ask because may be this is
one of those simplified explanations that hides a much more complex topic like
we see many times in Japanese.

Is there any hard to grasp rule to use wa instead of wo for emphasis, or can
you use wa instead of wo for emphasis in any sentence?




Short answer would be that you can use _ha_ instead of _wo_ in most cases.

One thing you need to be aware of is when Noun + ha can be the subject of the
verb.

For example, consider

  * Hon wo yomu _= (I) read books_.

You can use _ha_ (Hon ha yomu) to emphasize your reading books (implying not
reading mangas for example). Here _hon_ cannot be the subject of _yomu_ ,
whence no ambiguity.

Next consider

  * Kare no otouto wo mita _= (I) saw his brother_

Just using _ha_ here (Kare no otouto ha mita) would mean _His brother saw
(something)_ , implying he didn't. So _ha_ is understood as the subject/topic
marker in the standalone sentence.

On the other hand, in a conversation like

  * A-san minakatta?
  * Kare no otouto **ha** mita

Here _ha_ is understood as the emphasis/constrast of _wo_. Technically _Kare
no otouto ha mita_ is ambiguous because _kare no otouto_ can be subject or
object for _mita_ , but practically it is always disambiguated by contexts.

The _kare no otouto_ example suggests: you can most probably use _ha_ instead
of _wo_ when you are responding to someone, but it is not always possible to
use _ha_ when you start describing something. That is, if you want to start a
conversation about 'you saw his brother', using _wo_ is necessary.

And of course, there may well be many other cases where care needs to be
taken. So the other (boring) short answer would be, it depends on contexts.




Short answer would be that you can use _ha_ instead of _wo_ in most cases.

One thing you need to be aware of is when Noun + ha can be the subject of the
verb.

For example, consider

  * Hon wo yomu _= (I) read books_.

You can use _ha_ (Hon ha yomu) to emphasize your reading books (implying not
reading mangas for example). Here _hon_ cannot be the subject of _yomu_ ,
whence no ambiguity.

Next consider

  * Kare no otouto wo mita _= (I) saw his brother_

Just using _ha_ here (Kare no otouto ha mita) would mean _His brother saw
(something)_ , implying he didn't. So _ha_ is understood as the subject/topic
marker in the standalone sentence.

On the other hand, in a conversation like

  * A-san minakatta?
  * Kare no otouto **ha** mita

Here _ha_ is understood as the emphasis/constrast of _wo_. Technically _Kare
no otouto ha mita_ is ambiguous because _kare no otouto_ can be subject or
object for _mita_ , but practically it is always disambiguated by contexts.

The _kare no otouto_ example suggests: you can most probably use _ha_ instead
of _wo_ when you are responding to someone, but it is not always possible to
use _ha_ when you start describing something. That is, if you want to start a
conversation about 'you saw his brother', using _wo_ is necessary.

And of course, there may well be many other cases where care needs to be
taken. So the other (boring) short answer would be, it depends on contexts.

