【单选题】Scientists say they now have proof to support the old-fashioned advice that it's best to sleep on a problem. They say sleep strengthens the memory and helps the brain organize the masses of informatio...
【单选题】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.
【简答题】Scientists say they now have proof to support the old-fashioned advice that it's best to sleep on a problem . They say sleep strengthens the memory and helps the brain organize the masses of informati...