Avoiding Expletive Constructions

This sounds like something a politician has to learn to avoid, but, no, an expletive construction is a common device that often robs a sentence of energy before it gets a chance to do its work. Expletive constructions begin with there is/are or it is.

• There are twenty-five students who have already expressed a desire to attend the program next summer. It is they and their parents who stand to gain the most by the government grant.
  
• Twenty-five students have already expressed a desire to attend the program next summer. They and their parents stand to gain the most by the government grant.

http://grammar.ccc.commnet.edu/grammar/concise.htm