Mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 19 to 24.

There can’t be many people who are unaware of e-mail, even if they have never actually sent one. ___(1)___ 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 a very effective means of ___(2)___ 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 to be relatively informal. People are much more ___(3)___ to use language which they would consider unsuitable for a formal letter. Words spelled incorrectly in an e-mail are less likely to be checked than in a letter. One explanation for this is that ___(4)___ e-mail seems to be less permanent than something written on paper. We can be sure that the future development of e-mail will have all kinds of ___(5)___ effects on the way we ___(6)___.