1. Mozart's music is characterized by its naivety and clarity.
   莫札特的音乐特色是纯朴兴清澈。
2. He gets cheerful and depressed by turns.
   他的情绪高一阵低一阵.
3. To fasten by means of a hook or a hook and eye.
   用钩或钩眼扣固定
4. He is played out by overwork and worry.
   他因过分劳累和焦虑而精疲力竭。
5. The flooring and landscaping will be done by contractors.
   地板铺设和室外美化将由承包人来做。

　1个副词解释