tough源于古英语，其基本义是“strong and firm 结实的”，指材料的质地“结实的”，后逐渐衍生出指人“strong, powerful”，随后又衍生出了其他释义。理清各项释义间的联系可以帮助我们轻松记忆tough的各项释义。
You have to be tough to be successful in politics.
2. Ask for a helping hand to get you through the tough situation. (2012 全国)
3. Meanwhile, in those countries where the shawls (披肩) are sold, police are getting tough with the dealers.
4. Asparagus (芦笋) is by nature tender and tasty at one end, but gets tougher and difficult to eat at the other end.
5. Harvard researchers have created a tough, low-cost, biodegradable (可生物降解的) material inspired by insects’ hard outer shells. (2012 湖南)
6. It was then that I started to appreciate the tough choices she had to make on balancing family and work. (2014 天津)