I'm sorry. （假客氣的時候說，并不真的覺得抱歉。）
I'm sorry, but you don't know what you're talking about.
不好意思，你說什么？（你知道你自己在說什么嗎？）

sorry? （=pardon？）我沒聽懂，我沒聽清！
Sorry? what was that again?
不好意思，你剛才說什么？

Sorry？（質問的語氣）你說真的嗎？你說什么？

You'll be sorry. 你會后悔的。
If you don't finish your homework before mom gets home, you'll be sorry.
如果媽媽回家前你還沒寫完作業，你會后悔的。
You'll be sorry when your girlfriend finds out you went drinking last night.
要是你女朋友發現你昨晚出去喝酒了，你就會后悔的。
If you don't get that done, you'll be sorry.
要是你沒完成這件事，你會后悔的。

better safe than sorry 小心為上，不要事后后悔莫及
Put your seat belt on-better safe than sorry.
系好安全帶，不要事后追悔莫及。
Set the alarm clock-better safe than sorry.
訂好鬧鐘，不要到時候后悔。
Watch your purse-better safe than sorry.
看好你的包，不要到時候后悔。