We all like to use the word “cool”. You canuse it to say something is “new”， “wonderful” or“great”. Do you know some other cool words?Theyare perhaps “the Internet” and “e－mail”. Let'stalk about them now。

注：“本文中所涉及到的圖表、注解、公式等內(nèi)容請以PDF格式閱讀原文”