While other scientists are keeping____eye on changes in the H5N1 bird flu strain, the scientists in England are working on vaccines, in case it becomes highly infectious in ____humans.
I ______ the novel by the time you ______ back next week.
The number of the audience, ______ we had expected, was a thousand.
Having been born on the earth, we had no choice but ________ hospitality it offered.
The enemy troop could hardly make any advance, and ________ could they fall back.
An online survey at sina.com suggested more than four in five interviewers _______the Microsoft move would not be effective _________ software piracy.