Climbing Mount Everest great skills and not without risk.
| A．requires；are | B．required；were | C．requires；was | D．requires；is |
She had to drop out of school _____ her family couldn’t afford the cost of her education.
| A．although | B．unless | C．because | D．so |
The old man has retired from the factory. He _____ there for 30 years.
| A．works | B．worked | C．has worked | D．was working |
—I don’t mind telling you what I know.
—You _____. I can manage it myself.
| A．mustn’t | B．ought not to | C．can’t | D．don't have to |
The decorations were so lovely that they _____ in a short time.
| A．sold out | B．has been sold out | C．were sold out | D．were selling out |
The students _____ are hard-working and ready to help others should be praised.
| A．who | B．whom | C．which | D．whose |