1. It is no exertion to him to do so.
   这样做对他而言并不费力。
2. To tire with physical or mental exertion; weary.
   使疲劳因身体或精神费力而疲劳;劳乏
3. The doctor says he must avoid all exertion.
   医生说他必须避免做任何要用劲的事。
4. We reap a benefit from exertions.
   我们因努力得到利益。
5. Physical or mental weariness resulting from exertion.
   疲劳由于费力而引起的身体或精神上的虚弱

　1个名词解释