in the following sentence why は particle is used? Could I also use の in this sentence? Thanks.
彼は歯が白い.
in the following sentence why は particle is used? Could I also use の in this sentence? Thanks.
彼は歯が白い.
Basically, you should think of this as a set construct. XはYがZ. Of course, Z can be anything, not just an i-adjective, but in general when you see this construct, you should interpret it as:
Regarding X, Y is Z.
For example,
この街はお寺が多いです。
"There are many temples in this town". Or, literally, "Regarding this town, the thing that's 'many' is 'temple'".
And of course, you could say
彼の歯は白いです。
That would also be correct. However, please pay special attention that in my example above, there is a は particle, not the が particle there. There is a reason to that.
The reason is that the が particle emphasizes what comes before it, when the は particle describes what comes after it. So when you say
彼の歯は白いです。
you say "As for his teeth, they're white.". Describing what comes after the topic marker. This is actually the perfect substitution for your original sentence in question. Their meanings are the same with は.
In general, you can interpret the topic marker as:
AはB means "As for A, B.".
However, が works in a different way. With が, you can generally interpret things you see as
AがB means "The thing that's B is distinctly A [among all the other things in the context]".
So when you say
彼の歯が白いです。
this is going to be interpreted as
The thing that's white is his teeth.
Implying that, depending on context, his teeth are white and no other thing is white.
Or you could also say
彼のが白い歯です。
This means
"The white teeth are his" [and no other teeth are white in this context].
Implying that his teeth are white, and no other teeth are. For example, this could be used when there are 4 people in the room, and one of them has distinctly white teeth in comparison to other people's teeth. So you can't say 「彼の歯が白いです。」and expect it to mean the same, because it's used differently.
If you have any questions left, fire away in comments.
は emphasizes that the sentance applies to him in particular and not somebody else. The sentence relates to the conversation topic of him.
彼は歯が白い.
Consists of the first part ''彼は'':''As for him in particular and not somebody else'' and the main part of the sentence 歯が白い. ''teeth are White''. The first says what ''teeth are white'' relates to.
Meanwhile,
彼の歯が白い.
Only consists of one part. It Would be ''His teeth are white''. Here, the grammatical subject of the sentance (which is always marked with ga) isn't just ''teeth'' but instead ''His teeth''.