Do you know when the Great Wall _________?
| A．was come into being | B．came into being |
| C．had come into being | D．had been come into being |
You really need to go out and get some fresh air and sunshine. You ______ overworked during the last two weeks.
| A．have been | B．were | C．had been | D．would |
—How long do you think it will be ________ we win the football World Cup?
—Perhaps twenty years.
| A．when | B．since | C．that | D．before |
Silk from China found its way to India, the Middle East and Rome, _______ spices and glass, which was not known to China.
| A．in exchange for | B．in return | C．in change for | D．in need of |
Li Yang, the founder of Crazy English, says that he copies it down _______ he comes to a sentence.
| A．unless | B．while | C．because | D．every time |
This is the third time I _______ Beijing. The second time I ______ here was on Christmas Day last year.
| A．have visited; came | B．have visited; have come |
| C．visited; came | D．visited; have come |