To save people's lives，the doctors and scientists are risking their lives to do （医学的）research．
Our teachers often encourage us to face the difficulties （勇敢地） and try to overcome them．
When we are in danger， it's very important to make a good （决定）．
Make sure there are no （错误） in your test paper before handing it in．
Our head teacher always （鼓励） us to solve problems by ourselves．