They _____ for sixteen hours and still have a long way to go.
| A．had walked | B．have been walking |
| C．walked | D．had been walking |
Because so many visitors are visiting our school today, some teachers have to _______ guides.
| A．serve as | B．regard as | C．treat as | D．use as |
She thinks only of herself; she doesn’t _____ other people.
| A．care for | B．care about | C．care of | D．care in |
—Peter didn’t come to the meeting this morning.
— I _______ him yesterday, but I was too busy and forgot it.
| A．should have told | B．should tell | C．had to tell | D．had told |
I ________ it myself ________ your homework.
| A．prefer do; rather than copy | B．prefer doing; than copy |
| C．would do; rather than copy | D．would rather do; than copy |
____ he has made a decision, it is not easy for you to make him change his mind.
| A．Though | B．Unless | C．Once | D．Until |