You must apologize for that.

你必须为此道歉。

youdao

I must apologize to you.

我必须向您道歉。

youdao

I must apologize for it.

我必须为此而道歉。

youdao

Right here and now I must apologize to Fed Chairman Alan and former Treasury Secretary Bob for such bluntness--because I'm talking about you.

FORBES: BUBBLEHEAD ECONOMY

If you must take another call, apologize and if appropriate, reschedule your time together.

FORBES: Nine Leadership Resolutions for the New Year

As a result, I must assume personal responsibility for my words and apologize directly to those who have been hurt and offended by those words.

CNN: Statement from Mel Gibson