In some countries,you're supposed to (握手) with others for the first time.
他从来没走那么远, .
这个周末,威海有一场大型音乐会. .
为了安全起见,请不要到人群密集的地方. .
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.