完形填空。 Most of us can remember the days w

     Most of us can remember the days when we didn't use e-mail as an everyday vehicle for communication.
Slowly but surely, it crept (慢慢移动) into   1   . E-mail is a   2   tool for college students at any level. It's
available 24 hours a day,7 days a week and   3   at holidays. Most universities assign students an account
entrance,   4   there is usually not even an option (选择) involved.
     You can do everything from consulting on homework and projects,   5   classmates, family and friends,
and getting daily new services to  6   you informed of world  7   . But, what are the  8  ? E-mail can be e-jail.
You might   9   hours writing and replying to e-mails  10   you should be busy with the books for an upcoming
exam. 
  11   ,you might be signed up for so many daily services,   12   horoscopes (占星术), new services, or
personals, that your mailbox is so   13   "junk mail",that finding the  14  e-mails through your box might take
hours.
      If you're a student,  15   is precious. Create and organize your e-mail folders into important school-related
mail, correspondence (通信)with friends and family, and a folder for jokes, horoscopes and other new services. 
  16   put the mail into the proper folders first, and when you've finished, head for the important school-related
folder first. Respond to the most important e-mails first and,   17   you have time, you can get to the others. 
       18  your friends from forwarding those tiresome jokes, tiresome quizzes, and chain mails. The minute you 
  19   you've got one, delete it   20   so you won't be tempted to read it.