adj.发达的（国家或地区）；成熟的

• develop/ developing/ developed
  
  
  Ⅰ.develop既是及物动词，又是不及物动词，意为“发展”，“开发”。如：
  
  The child is developing well. 这孩子发育很好。
  
  Ⅱ.developing为现在分词，起形容词的作用，表示主动意义，意思是“发展中的”。如：
  
  ① China is a developing country. 中国是一个发展中国家。
  
  Ⅲ.developed为过去分词，起形容词作用，表示被动含意，意思是“发达的”。如：
  
  Japan ia a developed country. 日本是一个发达国家。
   

envelope/stamp/letter/mail/airmail/email/post/postage/postcode/postcard/zip/code/develop/developed/development/promote
记忆：
1. 词根velop [ vE5luE ]表示封闭，en-, 加强语气， 在里面；envelope [ 5envilEup ] n.信封, 封套, 封袋 Get me two large envelopes for the letters, will you? 给我买两个信封来装信，好吗？
2. develop [ di5velEp ] de-, 去掉，develop, 去掉封闭，vt. 发展, 发达, 冲洗, 显影 IT is developing so fast that the product will be out of date in just one month. 信息技术发展很快，信息产品仅仅一个月就会过时。
3. developed adj. 发达的 Generally speaking, the coastal cities are more developed than the inland ones.一般说来，沿海城市要比内陆城市发达。
4. development [ di5velEpmEnt] n. 发展 The theme of the world is still peace and development.世界的主题仍然是和平与发展。
5. promote [ prE5mEut ] vt. 促进, 发扬, 提升, 提拔 The governments are trying to promote the friendship between the two countries. 政府正在努力促进两国友好关系的发展。
6. stamp [ stAmp] n. 邮票, 图章，跺脚 n. 跺(脚) I need one more stamp to post these letters.寄这些信还差一张邮票。
7. letter [ 5letE ] n. 字母, 信函, 文学（letters） The man of letters is often admired here.在这儿作家常常受到赞赏。
8. mail [ meil ] n. 邮件, 邮政 vt. 邮寄(美) There is a mail addressed to you. 有一个给你的邮件。
9. email [ i5meil ] n. 电子邮件 We often keep in touch with each other by email. 我们常通过电子邮件保持联系。
10. airmail [ 5ZEmeil] n. 航空邮件 I would like to send the letter by airmail.我想空邮这封信。
11. post [pEJst] n. 邮件，邮政，柱, 岗位, 职位 vt. 张贴, 邮递（英） He holds an important post in the company. 他在公司担任要职。
12. poster [ 5pEustE ] n. 海报, 招贴 The posters for the concert have been put up here and there.到处都张贴有音乐会的海报。
13. postage [ 5pEustidV] n. 邮资 Sorry. I can’t afford the postage right now.对不起，我现在付不起邮资。
14. postcode [5pEJstkEJd] n. 邮递区号（英） The postcode helps the post office to sort the mails quickly.邮政编码有助于邮局很快地分选邮件。
15. zip code n. 邮递区号(美)
16. postcard [5pEJstkB:d] n. 明信片 More and more people send greetings by email instead of postcards, which is more friendly to our environment.越来越多的人用电子邮件代替了明信片来表达问候，这对我们的环境更有利。
另类阅读：
With the development of modern science, fewer and fewer people mail letters in the form of envelope with a stamp on it. Most of us use email instead. It needs no postcode and costs us much less postage.