As an explanation of how to use the particles "は"
and "が"
properly, classifies into 5 categories.
(1) Depending on whether it is new information or old
information.
In conversations and contexts, if the nominative noun is
unknown (= new information), it is expressed using "ga", and if it is
known (= old information), it is expressed using "ha".
・ 鈴木さんは校長です。Mr.
Suzuki is the principal. (Since "Mr. Suzuki" is "known", it
is indicated by adding "ha")
・ 鈴木さんが校長です。Mr.
Suzuki is the principal. (Since it is "unknown" who the principal is,
"Mr. Suzuki" is indicated by adding "ga")
(2) Depending on whether it is a phenomenon sentence
or a judgment sentence.
A sentence that expresses a phenomenon as it is without
adding the speaker's subjective judgment is called a "phenomenon
sentence", and the nominative case of the phenomenon sentence is
"ga". On the other hand, a sentence expressed by the speaker adding
subjective judgment to the phenomenon is called a "judgment
sentence", and the nominative case of the judgment sentence is
"ha".
・
(Looking at the dog in front of you) 犬が寝そべっている。The dog
is lying down. (Phenomenon sentence)
・
(Pointing to an umbrella that was about to be taken by another person by
mistake) それは私の傘です。It is my umbrella. (Judgment
sentence)
(3) Depending on whether
how far the main topic is related (= connected), whether it is related to the
end of the sentence, or whether it is related only to the clause.
It is a method to use properly based on the fact that
"ha" is used when the nominative case extends to the end of the
sentence, and "ga" is used when it is related only to the clause.
・ 父が晩酌をするとき、つきあうWhen my
father has an evening drink, I go out with him.
・ 父は晩酌をするとき、冷や奴を食べる When my
father has an evening drink, he eats cold tofu.
(4) Depending on whether the nominative case expresses the
meaning of contrast or the meaning of exclusion.
When the nominative case has the meaning of contrast,
"compared to," for the same type of noun that does not appear in the
sentence, "ha" is used (contrast "ha"). ), "Ga"
is used when it has the exclusive meaning of "that is only
・ 犬は好きだが、猫は嫌いだ。I
like dogs, but I don't like cats. (Represents the meaning of contrast)
・ 私が責任者だ。I am the person in charge. (In the
sense of exclusivity that I am the only person in charge, not the others here)
(5) Depending on
whether it is designated sentence or the measures sentence.
A predicate such as 「貴乃花は横綱だ」"Takanohana
is Takanohana" The predicate represents the title of the nominative noun,
and a sentence that cannot be rephrased as 「横綱が貴乃花だ」"Yokozuna
is Takanohana" is called a "measures sentence", and
"ha" is used in the measures sentence. On the other hand, a sentence
that indicates that the predicate noun is the same as the nominative noun, such
as
「鈴木さんはあの人だ」
"Mr. Suzuki is that person," and is paraphrased as 「あの人が鈴木さんだ」"that
person is Mr. Suzuki," is a "designated sentence." ,
"Identification sentence", and "ha" and "ga" can
be used in this kind of sentence.
・ 地球は、太陽系の惑星だ。（Earth is
a planet in the solar system. (Measures)
・ あの人の趣味は、勉強だThat
person's hobby is studying. (Designated sentence)
