a. 值得花时间的, 值得做的, 有真实价值的

◆记忆方法一：
联想方式：worth（价值；值钱的）；while（时间）
记忆方法：有价值的时间，说明是值得做的。

• worth, worthy, worthwhile用法区别
  
  worth, worthy, worthwhile用法区别
  
  区别1
  worth表示“值，值得”，可用表语或后置定语，其后一定要有名词或动名词作宾语，但不能接不定式。如：
  The book is worth $ 100.这本书值100元。
  The book is worth reading.这本书值得看。
  This is a book worth reading.这是一本值得读的书。
  区别2
  worthy表示“应得，配得上，值得”，常作表语或后置定语，后接不定式，或of加名词或动名词。如：
  His behaviour is worthy of great praise. 他的行为应受到高度赞扬。
  I think he is not worthy of her. 我认为他配不上她(from www.yygrammar)。
  The book is worthy of being read. = The book is worthy to be read.这体书值得读。

value/evaluate/assess/assessment/valuable/invaluable/valueless/priceless/precious/worth/worthy/worthwhile/worthless/treasure/jewel/jewelry
记忆：
1. value [ 5vAlju:, -ju ] n. 价值 vt. 珍惜, 评价, 重视 No one can tell the exact value of love. 没有人能准确说出爱的价值。格言： If a job's worth doing, it's worth doing well. 值得做就要好好做。
2. evaluate [ i5vAljueit ] vt. 评价, 估计 The house is evaluated to be worth three million yuan. 这房子估价三百万。
3. assess [ E5ses ] To determine the value, significance vt. 估定, 评定 The school will assess every teacher’s work at the end of each school year. 每学年末学校都要评估每位老师的工作。
4. assessment [ E5sesmEnt] n. 评估, 评估的款额 [税额]，看法 What is your assessment of the situation?你对形势有什么看法？
5. valuable [ 5vAljuEbl ] adj. 贵重的, 有价值的 I find his advice valuable. 我觉得他的建议有价值。
6. valueless adj. 不足道的 What they found was just some valueless coins. 他们发现的只是一些没什么价值的硬币。
7. invaluable [ in5vAljuEbl] adj. 无价的, 价值无法衡量的 Devotion is invaluable. 爱的无价的。
8. priceless [ 5praislis ] adj. 无价的, 极贵重的 Actually, Mona lisa by Da Vincy is priceless. 实际上，达芬奇画的《蒙娜丽莎》是无价之宝。
9. precious [ 5preFEs ] adj. 宝贵的, 贵重的 Gold is a kind of precious metal. 黄金是一干贵重金属。
10. worth [ wE:W ] n. 价值, 财产 adj. 值钱的, 值……的 be worth doing值得做 Love those who are worth loving. 要爱那些值得爱的人。
11. worthy [ 5wE:Ti ] adj. 有价值的, 应. . . 的, 可敬的, 值得的 I don’t think such a fashion girl worthy of being loved.我认为这样的时尚女孩并不值得爱。 be worthy to be done 或be worthy of being done值得做
12. worthwhile [ 5wE:T5(h)wail ] adj. 值得做的, 值得出力的 It’s worthwhile that we spent so much time helping the trapped panda. 我们花那么多的时间救受困的大熊猫是值得的。
13. worthless [5w:WlIs] adj. 无价值的, 无益的 Not all the waste is worthless. Some can be recycled. 并非所有的废物都没有价值。一些东西可以再回收。
14. treasure [ 5treVE ] n. 财宝, 财富, 珍品 vt. 珍爱, 珍惜 Treasure real friendship and make real friends. 珍惜真正的友谊，交真正的朋友。
15. jewel [ 5dVu:El ] n. 宝石 The jewels he discovered made him rich overnight.他发现的珠宝使他一夜暴富。
16. jewelry [5dVu:ElrI] n. 宝石（总称，不可数名词） Later, he ran a jewelry shop in New York. 后来，他在纽约开了一家珠宝店。
另类阅读：
Friendship is worth valuing. I think it is more valuable than any precious jewel. It’s priceless. It is worthy to be called most invaluable treasure in our life.