afraid(SORRY)
I'm afraid I'm not a very good advertisement for the diet since I've actually put on weight!恐怕我不是这套减肥饮食计划的活广告，因为我的体重实际上是增加了！
I'm afraid physics will always be a closed book to me.恐怕我对物理永远是一窍不通了。
I'm afraid I disagree with you on several counts.
I'm afraid those days are gone and they'll never come again.恐怕那样的日子一去不复返了。
My culinary skills are rather limited, I'm afraid!