Since you have made such good preparations,there _______ be any problem about passing the coming exam.
| A．mustn’t | B．shan’t |
| C．shouldn’t | D．needn’t |
Only when he had done it ______ that he had made a mistake.
| A．he then realized | B．did he realize | C．before | D．he realized |
---Would you mind if I opened the door?
--- ________________.
| A．Yes, go ahead | B．No, go ahead | C．Yes, please | D．Never mind |
It is demanded that you ____ at six.
| A．will arrive | B．arrive | C．arrived | D．would arrive |
At present，there is little doubt ________ short message plays an increasingly important role in our lives．
| A．whether | B．if | C．that | D．which |
— Are you a teacher?
— No, but I ______. I worked in a middle school for three years.
| A．am | B．will | C．do | D．was |