2. I can't express how devastated I am that this happened...
3. This happening has completely knocked me for six! My profuse apologies for this!
1. ..so, so.. We use this form when wishing to add stress to an adjective.
"James is so, so strong!"
2. I can't express how + adjective = We use thiis construction to add emphasis to the given adjective. "I can't express how happy I am to hear of the b irth of your new baby!"
3. to be knocked for six = knock somebody for six. (British & Australian informal) to surprise and upset someone a lot
"It really knocked me for six when my ex-boyfriend announced he was getting married"
1. ..so, so.. これは形容詞を強調したいときに使う副詞として機能します。
例"James is so, so strong!"
2. I can't express how + adjective = これは、howの後に来る形容詞を強調したいときに使う構文です。
例"I can't express how happy I am to hear of the birth of your new baby!"
3. to be knocked for six = イギリス、オーストラリアで使われます。誰かを怒らせたり驚かせたりすることを言います。
例"It really knocked me for six when my ex-boyfriend announced he was getting married"
Sincere - proceeding from genuine feelings
Regret - feeling sadness or disappointment over something one has done or something that has happened
Wholeheartedly - with complete honesty
_________________________________________________________
Examples
I apologize wholeheartedly for failing to let you know that the meeting has been cancelled.
Please accept my sincere apology for the late response.
I apologize wholeheartedly for the inconvenience.
Sincere
- 本心から来る
Regret
- 行ったことや起こったことに対する悲しみや失望を感じる
Wholeheartedly
- 真っ正直に
_________________________________________________________
例
I apologize wholeheartedly for failing to let you know that the meeting has been cancelled
（会議の中止をお知らせしなかったことを心からお詫び申し上げます）
Please accept my sincere apology for the late response
（返信が遅くなり誠に申し訳ございません）
I apologize wholeheartedly for the inconvenience
（ご不便をおかけし心からお詫び申し上げます）
You can use any of these :
"Please accept my apologies."
"Please accept my sincere apologies for…"
"I would like to express my deep regrets for…"
"Please accept my apology for…"
"I’m particularly sorry for…"
"Please allow me to apologize for…"
"Please accept this as my formal apology for…"
”Please accept my apologies"
＝お詫び申し上げます。
”Please accept my sincere apologies for"＝
「○○について、深くお詫び申し上げます。」
"I would like to express my deep regrets for"＝
「○○に関して、遺憾の意を表します。」
"I'm particularly sorry for"＝
「特に○○に関しては、大変申し訳なく思っております。」
”Please allow me to apologize for"=
「○○に対し、お詫びさせて下さい。」
”Please accept this as my formal apology for"＝
「どうか、これを○○に対する正式な謝罪として受け入れて下さい。」
If you want to express the fact that you are very sorry for something, especially in a business email, you can say:
"I sincerely apologize."
"Please accept my sincerest apologies."
特にビジネスメールで、深いおわびを表したいときは、次のように言えます。
"I sincerely apologize."
"Please accept my sincerest apologies."
（深くお詫びします）
アメリカ合衆国 
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日本 
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