意味のない it(天気・時間・仮主語)The Empty It: Weather, Time, and Placeholders
代名詞 / Pronouns
It's raining.(雨だ)の it は何も指していません。英語の文は主語の席が空席禁止なので、指すものがないときは「空の it」が席を埋めます。天気・時間・距離、そして It's easy to make mistakes. の仮主語まで、ぜんぶ同じ席埋め要員です。
The it in It's raining points at nothing. English refuses to leave the subject seat empty, so when there's nothing to point at, an empty it sits down and holds the seat — for weather, time, distance, and the placeholder in It's easy to make mistakes.
主語の席は空席禁止
No Empty Seats in English
日本語は「雨だ」「9時だ」と主語なしで言えます。英語は(命令文を除き)文の先頭に主語の席があり、必ず誰かが座らなければならない。指す相手がいない文では、意味ゼロの it が席を埋めます。だからこの it は訳しません。「それは雨です」と訳した瞬間、正体を見失います。なお、くだけた話し言葉では Sounds good.(いいね)、Doesn't matter.(気にしなくていいよ)のように主語を落とすことがありますが、これは会話でだけ許される省略です。書き言葉では席を空けません。
Japanese happily says 雨だ or 9時だ with no subject at all. English — imperatives aside — builds every sentence with a subject seat up front, and someone must sit in it. When there's nothing real to refer to, a meaning-free it takes the seat. That's why this it never gets translated: render it as それ and you've lost the plot. (Casual speech does clip the subject off short replies: Sounds good. Doesn't matter. That is a conversational shortcut, not a written option.)
It's almost ten. It takes twenty minutes to get there.
もうすぐ10時だ。そこまで20分かかる。
時間・所要時間も担当。Time and duration are on its beat too.
It's easy to make mistakes here.
ここは間違えやすい。
仮主語の it。本体は後ろの to make mistakes。Placeholder it — the real subject waits behind: to make mistakes.
空の it
指す相手なし。天気・時間・距離・仮主語。Refers to nothing — weather, time, distance, placeholders.
It's a long way to the station.
駅までは結構ある。
ふつうの it
登場済みの物を指す(one-vs-it 参照)。Points at an established thing.
Where's my phone? Oh, it's on the table.
スマホどこだ? ああ、テーブルの上だ。
よくある間違い / Common Mistake
×Is raining today, so take an umbrella.
今日は雨だから、傘持っていきなよ。(のつもりで)
○It's raining today, so take an umbrella.
今日は雨だから、傘持っていきなよ。
日本語の「雨だ」の感覚で主語を落とすと、英語では席が空いたままの不完全な文になります。指すものがなくても it を置く——書き言葉では、命令文以外に主語の席の空席は許されない、が英語の掟です(後半の take an umbrella は命令文なので主語なしでOK)。
Drop the subject the way Japanese does and the English sentence sits there with an empty seat. Even with nothing to refer to, the it must be seated. In writing, no empty seats outside imperatives — that's the law. (The second half, take an umbrella, is an imperative, which is why it goes subject-free.)
It takes ...(時間が)〜かかる所要時間の定番。It takes ten minutes. / It took forever.(死ぬほどかかった)The duration formula: It takes ten minutes. It took forever.
It looks like ...〜みたいだね空模様にも見立てにも。It looks like rain.(ひと雨きそう)For skies and situations alike: It looks like rain.
It turns out (that) ...ふたを開けてみると〜だった結末の判明を運ぶ席埋め it の定番。The seat-filler delivering how things turned out.
It's no use -ing〜してもむだだ仮主語+動名詞の慣用。It's no use crying over spilt milk.(覆水盆に返らず)Placeholder plus gerund: It's no use crying over spilt milk.
まとめ / Summary
書き言葉では主語の席は空席禁止(命令文は例外)。埋めるのが空の it。In writing, no empty subject seats (imperatives excepted) — empty it fills them.
天気・時間・距離・明暗は it の担当。訳さない。Weather, time, distance, light — its beat. Never translate it.
仮主語 It's ... to do は「軽い頭・重い尻尾」のリズム作り。Placeholder It's … to do keeps the light-head, heavy-tail rhythm.
It takes ... で所要時間。持ち歌にする。It takes … owns duration — make it yours.