Choose the best answer: on in at of

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 23 to 27.

The use of computers has meant that students can study language programmes (23) _________ their own  speed  when  and  for  how  long  they  want.  What’s  more,  in  the  virtual  classrooms  of  the  future  the student will put on their headset, and be transported into an imaginary school, choose their class, take the books  they  need  off  the  shelf  and  hold  conversations  with  other  computerised  students.  They  might instead choose to pay a visit to the supermarket or the train station, the bank or the restaurant. At the (24) _________ of a button they would be transported to (25) _________ realistic settings where they could practice  their  English,  maybe  getting  a  hand  from  a  virtual  English  companion.  All  this  perhaps,  at  the computer,  from  the  comfort  of  their  home:  no  (26)  _________to  catch  the  bus  to  college,  or  a  plane  to England.  Exciting?  Certainly,  and  it’s  an  interesting  alternative  to  traditional  classroom  lessons.  But would it ever (27)_________the classroom? Hopefully not. Surely the need to relate to real people talking about  real  issues  and  generally  learning  a  little  more  about  others  will  always  lead  language  learners  to uzcx be exc eg at least a little of their time with real people.

• A. on
• B. in
• C. at 
• D. of