Read the passage and mark the letter A, B, C or D to indicate the best answer for each of the following blanks.

There can't be many people ___(1)___ are unaware of e-mail, even if they have never actually sent one. ___(2)___ there are some similarities between e-mail and letters, there are also many differences. The first is that e-mail is delivered instantly, so it can be ___(3)___ very effective means of ___(4)___ when speed is important. This speed means that e-mail is more practical for communicating over large distances. Another difference is that e-mail tends ___(5)___ relatively informal. People are much more ___(6)___ to use language which they would consider unsuitable ___(7)___ a formal letter. Words spelled incorrectly in an e-mail ___(8)___ less likely to be checked than in a letter. One explanation for this is that an e-mail seems to be less permanent than something written on paper. We can be sure that the future ___(9)___ of e-mail will have all kinds of unexpected effects ___(10)___ the way we communicate.