From time to time a crocodile has snatched someone _______ he or she is even aware that the crocodile is there.
| A．when | B．until | C．since | D．before |
When we were young, every evening my brother and I____ stay at home waiting for our mother.
| A．would | B．might | C．should | D．could |
We arranged to meet at 8:00, but she never ______.
| A．turned down | B．turned off | C．turned over | D．turned up |
Missing the flight means _______ for another three hours.
| A．waiting | B．to wait | C．wait | D．to be waiting |
After I had finished eating, he advise me ______ immediately.
| A．set off | B．set aside | C．set down | D．set about |
-----This returned Chinese scholar has become one of the top experts in this field.
-----Yes, I know him very well. He _____ in Africa with wild animals for eight years.
| A．is working | B．had worked | C．worked | D．has been working |