_________several times, but Mary still has no idea of how to do it properly.
| A．Being shown | B．Having shown | C．Having been shown | D．I’ve shown her |
—Are you going to the concert next week?
—I’d like to, but I ______ an exam then.
| A．take | B．took |
| C．was taking | D．will be taking |
—I didn’t know you play the piano. It sounds wonderful!
—Thank you! I ______ it when I worked in UK.
| A．learned | B．had learned |
| C．have learned | D．learn |
We are going to the theater tomorrow ______ all the tickets are sold out.
| A．when | B．unless |
| C．whether | D．because |
Once ______, the book will surely attract readers’ attention since it is related to people’s health.
| A．publishing | B．having published |
| C．published | D．to publish |
—I am worn out now. I stayed up last night to finish the report.
—Oh? You ______. The professor asked us to hand it in next week.
| A．needn’t have | B．wouldn’t have |
| C．couldn’t have | D．can’t have |