---You haven't lost the concert ticket, have you?--______. I know it is not easy to get another one at the moment, but nowhere can I find it.
I regret _____ hard at school, or I would have succeeded in passing the exam.
. We should prevent such a silly mistake _____ again.
_____ full preparations, we decided to put off the meeting till next week.
I’m examining the article he has just finished _____ the possible mistakes in it.
Having passed all the tests, she felt a great weight _____ off her mind.