not only A but also B(文頭に出すと倒置)Not Only That, But It Flips the Verb
接続詞 / Conjunctions
not only A but also B は「A だけでなく B も」。also は省いても構いません。注意すべきは文頭に出したときで、Not only did he apologize, … のように倒置が起きます。否定の語句を副詞として文頭に置いたら、主語と助動詞をひっくり返す——英語の決まりごとです。
Not only A but also B means A, and B on top of it. You can drop the also. The thing to watch is what happens when not only opens the sentence: "Not only did he apologize, …" The verb flips ahead of the subject. Send a negative expression to the front as an adverbial and English inverts.
前に出したら、ひっくり返す
Front It, Flip It
not only は文の途中に置くのが基本です。He not only apologized but also offered to pay. これなら倒置は起きません。強調したくて文頭に持ってくると、英語は「否定語が先頭に来た」と判断して疑問文と同じ語順に切り替えます。Not only did he apologize … の did がそれです。倒置が起きるのは前半だけで、but 以下は普通の語順に戻ります。
The default slot for not only is mid-sentence: "He not only apologized but also offered to pay." No inversion there. Move it to the front for emphasis and English reads the opening as a negative, switching into question word order. That's the did in "Not only did he apologize …" Only the first half inverts; everything after but goes back to normal.
置き場所で語順が変わるThe slot decides the word order
He not only apologized but also offered to pay.
彼は謝っただけでなく、支払いも申し出た。
文の途中に置いた形。倒置なし。いちばん無難。The mid-sentence slot. No inversion, and the safest choice.
Not only did he apologize, but he also offered to pay.
謝っただけではない。支払いまで申し出たのだ。
文頭に出したので did が主語の前へ。書き言葉と演説で使う。Fronted, so did jumps ahead of the subject. Writing and speeches like this shape.
Theなぜ the なのか【その場で一つに決まる】話し手と聞き手のいる状況で、どれを指すか一つに決まるから the。日本語なら「（例の）」「うちの」を補って読むと感覚が近い。 film is not just long but genuinely dull.
その映画は長いだけでなく、本当に退屈だ。
会話では not just ... but ... のほうが自然。also も省ける。Speech prefers not just … but …, and the also can drop out.
文の途中(倒置なし)
語順はそのまま。会話でも書き言葉でも使える。迷ったらこちら。Word order stays put. Fine in speech and writing alike, and the safe default.
She not only writes the code but also tests it.
彼女はコードを書くだけでなく、テストもする。
文頭(倒置あり)
疑問文と同じ語順にする。硬い響きになるので多用しない。Takes question word order. It sounds formal, so don't reach for it often.
Not only does she write the code, but she also tests it.
彼女はコードを書くばかりか、テストまでやる。
よくある間違い / Common Mistake
×Not only he apologized, but he also offered to pay.
謝っただけでなく、支払いも申し出た。(のつもりで)
○Not only did he apologize, but he also offered to pay.
謝っただけでなく、支払いも申し出た。
文頭に出したのに倒置していない形です。not only のような否定の語句を先頭に置いたら、主語と助動詞をひっくり返します。一般動詞なら do / does / did を補って、その後ろは原形に戻す(apologized ではなく apologize)。倒置を書くのが面倒なら、そもそも文頭に出さず He not only apologized … とすれば問題は起きません。同じ倒置は Never / Rarely / Little / Only then を文頭に置いたときにも起こります。この倒置の仕組みそのものは「否定語を文頭に出すと倒置が起きる」の項にまとめてあるので、ここでは not only の形だけ押さえてください。
This fronts not only but forgets to invert. When a negative expression opens the sentence, the subject and auxiliary swap places. With an ordinary verb you supply do, does, or did, and the main verb returns to its base form: apologize, not apologized. If the inversion feels like a nuisance, just don't front it, and "He not only apologized …" sidesteps the whole issue. The same flip applies after Never, Rarely, Little, and Only then. The mechanism itself gets its own entry, on fronted negatives and inversion; here, just learn the not only shape.
not just ... but ...〜だけでなく〜もnot only の会話版。倒置を伴わない位置で使うのが普通。The spoken form of not only, normally used in the slot that needs no inversion.
as well as〜と同様に、〜も重心は前の語にある。動詞は前の語に合わせる。The weight sits on the first item, and the verb agrees with it.
let alone ...まして〜など否定文で使い、後ろにより極端な例を置く。He can't ride a bike, let alone drive.Follows a negative and adds a more extreme case: "He can't ride a bike, let alone drive."
on top of thatその上さらに接続副詞なので前をピリオドで切る。会話で頻出。A connective adverb, so the sentence before it ends. Common in speech.
まとめ / Summary
not only A but also B。also は省いてよい。Not only A but also B, and the also is optional.
文頭に出したら倒置。一般動詞には do / does / did を補う。Front it and you must invert, supplying do, does, or did with ordinary verbs.
倒置は前半だけ。but 以下は普通の語順。Only the first half inverts; after but, word order is normal.
as well as は重心が前にあり、動詞も前の語に合わせる。As well as puts the weight on the first item, and the verb follows it.