---The president _____ by his doctor today that his cancer has come back.
| A．informs | B．has informed |
| C．has been informed | D．is being informed |
As the sea ice melts sooner each swimmer,polar bears are forced to come ashore earlier and face food shortages _____ they have stored enough fat to last them through the season.
| A．before | B．unless | C．since | D．until |
—What did he want to know,Anne?
—_______I could finish writing the report.
| A．When it was that | B．It was when that | C．It was when | D．When was it that |
Ladies and gentlemen,please fasten your seat belts,the plane______.
| A．takes off | B．is taking off | C．is going to take off | D．is to take off |
Without facts,we can’t form a correct opinion,for we need to have actual knowledge____ our thinking.
| A．which to be based on | B．on which to base |
| C．which to base on | D．which to base |
With a good ______ of both Chinese and English,she had an advantage over the other interviewees.
| A．program | B．guidance | C．command | D．ability |