Culture-oriented Common Days>Communication-gaps>
Distinction between "wa", "ga" and "mo"

"(wa)" is used to assign the subject of a sentence following it in most usual cases(whose purpose is to specify the predicate), especially in cases subject has other candidate(s) and predicate varies in relation to the subject's selections.
It is also used to exclude certain candidate from subjects.
English Japanese
Official languages in Canada are English and French. カナダの公用語英語とフランス語だ。
Hope after retirement is a scarce pension. 老後の支え僅かな年金だ。
He committed a serious crime. 重罪を犯した。
For me, coffee. コーヒー。
He rather is a commedian. むしろコメディアンです。
Partner is helpful on a journey, and sympathy is important on the life. 道連れ、世情け。
I suspect that although most of them are innocent, she at least must be guilty. 大半の人無実だが、彼女だけ有罪だと思う。
It is not always so. そうと限らない。

"(ga)" is used in simple sentences following the subject to specify subject itself than the predicate.
English Japanese
It's me who will be the representative of the miss-contest. ミスコンの代表になるのよ。
It's me who ordered cappuccino. カプチーノを頼みました。
Not she but he must be the principal offender if so. そういうことなら彼女でなく彼主犯でしょう。
The last chance is now. 最後のチャンスだ。
I'd like a girl for it. Not a boy. 女の子良い。男の子困る。
Most of them are no good, although this piece only is acceptable. ほとんどダメだ。この品物だけ良いが。
I only love this piece among his works, for all I don't care for others. 私は、彼の作品ほぼどうでも良いが、この作品だけ好きだ。

"(ga)" is used in compound sentences especially in the condition-defining part following the inner-subject of that part. It is also used in a result-defining part that has rather unexpected selection on the inner-subject.
English Japanese
I am sad if it is true. それ事実なら私辛い。
I will live strong even if it is true. それ事実で強く生きる。
If it rains tomorrow, please stay by me. もしも明日雨ならば、傍に居て。
If it is a cat, I will progress, and, if it is a tiger, I will flee. それネコなら私進み、それトラなら私逃げる。
If it is a cat, I will progress, and, even if it is a tiger, I won't flee. それネコなら私進むが、それトラで逃げない。
If wind blows, leaves scatter. 吹けば、木の葉散る。
If wind blows, tab-shops gain profits. 吹けば、桶屋儲かる。(A famous example of an absurd causality.)

"(ga)" is used in the clauses following the inner-subject of the clause as following.
"(no)" can replace it if the clause is used as the modifier of a noun.
case English Japanese
the clause is the
modifier of the subject
Those who lie a lot are not relied on. 多い人信用されない。
Those with brown feather are female.
→ Ducks whose feather is brown are female.
→ 羽茶色いのメスだ。
It is after a long while that she sings on the stage.
→ An occasion that she sings on the stage is after a long while.
→ 彼女舞台で歌うの久しぶりだ。
the clause is the
modifier of an object
Audience waits me sing on the stage.
→ Audience waits the moment when I sing on the stage.
→ 聴衆ステージで歌うのを待っている。
the clause is
Elephant has a long nose.
→ Elephant is an animal whose nose is long.
→ 象長い。
I dislike that actress. あの女優嫌いだ。
I lost a favor on him. 彼に愛想尽きた。
the clause is the
I suspect that she is the criminal. 彼女犯人だと思う。

"(mo)" is used in the sentences that leads to the same or alike result(like "too") for more or equal two matters or a wide range of selections (I learned in school that there are two different kinds: "identical-mo" and "astonishing-mo". But thus, it is consolidated in a unique category).
English Japanese
Men are said to be no exception to write a diary. 日記を書くらしい。
Women would do it also. するのだ。
So, you fairly like it! あんた好きねえ。(As a simple logic, "" should rather be used here. However, device to obscure the teller's opinion on what the world's majority is is some tenderness and taste of such a saying. Or, the teller may be deploring the world's recent tendency.)
Anything is useless, whatever you do. 何をして無駄だ。
For me too, coffee. コーヒー。
No one is to blame. 誰のせいでない。
Even storm is not fearful. 怖くない。
Storm blows, and, rain falls. 吹けば、雨降る。