______ you are supposed to do ______ you don't like a thing is ______ it. Don't complain.
| A．That; what; change | B．When; that; to change |
| C．What; when;to change | D．What; that; changing |
32. ---Why on earth didn’t you answer the phone?
---I’m sorry, but the doorbell _____ too.
| A．is ringing | B．was ringing | C．rang | D．was about to ring |
31. _____ our earth, otherwise it will be no longer fit for us to live on.
| A．Protected | B．To protect | C．Protecting | D．Protect |
30. ---They are quiet, aren’t they?
---Yes. They are accustomed _____ at meals.
| A．to talk | B．to not talk | C．to talking | D．to not talking |
29. _____ the project as planned, we’ll have to work two more hours a day.
| A．Completing | B．Complete | C．Completed | D．To complete |
28. --- Is Bob still performing?
--- I’m afraid not. He is said _____ the stage already as he has become an official.
| A．to have left | B．to leave | C．to have been left | D．to be left |