I'm sorry but I have a family matter to take care of.
很抱歉，我有家庭私事需要处理。
这是在因家里有事需要缺勤或早退的情况下使用的句子。通常，如果使 用了 family matter或者personal issue这样的字眼，对方就不会打破砂锅问 到底了。所以，这种借口最好不要经常使用。
I'm sorry but I have a family matter to take care of today. It looks like it will take all day to handle, so I don't believe I'll be able to come in at all today.
很抱歉，今天我有家庭私事需要处理，可能要花一整天的时：: 间，所以我今天恐怕不能来上班了。

I forwarded the e-mail to you by mistake.
我错误地把邮件转发给了您。
by mistake的意思是“失误地，错误地”。经常使用电子邮件的话，难免 会出现错发邮件的情况。
I forwarded the e-mail to the wrong person by mistake!
我把邮件发错人了！
I deleted your e-mail by mistake!
我错删了您的邮件！