---Why you are so worried?
--- I ___for my little son all the afternoon, I don’t know why he hasn’t come back so late.
| A．am waiting | B．have waited | C．have been waiting | D．waited |
I regret _____ hard at school, or I would have succeeded in passing the exam.
| A．not to work | B．having not worked |
| C．to have not worked | D．not having worked |
We should prevent such a silly mistake _____ again.
| A．occurring | B．to occur |
| C．to be occurred | D．from being occurred |
_____ full preparations, we decided to put off the meeting till next week.
| A．We did not make | B．Having not made |
| C．We had not made | D．Not having made |
I’m examining the article he has just finished _____ the possible mistakes in it.
| A．being corrected | B．to correct |
| C．corrected | D．having corrected |
Having passed all the tests, she felt a great weight _____ off her mind.
| A．taking | B．taken | C．take | D．to be taken |