Topic first: set the scene, then comment on it
Japanese sentences often open with “as for X” and then say something about it.要点The idea
Many sentences open with a topic marked by は (“as for X…”) and then comment on it.象ぞう は 鼻はな が 長ながい。zou wa hana ga nagai.
Polite象ぞう は 鼻はな が 長ながい です。zou wa hana ga nagai desu.
Elephants have long trunks.The famous example: as for elephants, the trunk is long. The topic (elephants) and the subject (the trunk) are different. Inside the frame sits the core sentence, 鼻はなが長ながい: a subject with が, plus its verb, adjective or noun + です.今日きょう は 天気てんき が いい。kyou wa tenki ga ii.
Polite今日きょう は 天気てんき が いい です。kyou wa tenki ga ii desu.
The weather's nice today.As for today: the weather is good.日本にほん は 電車でんしゃ が 便利べんり です。nihon wa densha ga benri desu.
Casual日本にほん は 電車でんしゃ が 便利べんり だ よ。nihon wa densha ga benri da yo.
Trains are convenient in Japan.As for Japan: trains are convenient.A昨日きのう その 本ほん を 読よんだ。kinou sono hon o yonda.I read that book yesterday.
Bその 本ほん は 昨日きのう 読よんだ。sono hon wa kinou yonda.That book: I read it yesterday.
- A何なに に する？nani ni suru?What are you getting?
- B私わたし は ラーメン。watashi wa raamen.I'll have ramen.
- C僕ぼく は カレー。boku wa karee.Curry for me.