Expletives, or expletive constructions, are generally considered unnecessary because they tend to make sentences wordier and more complex than they need to be. Most expletives are related to "to be" verbs that are used in "it is" and "there is" phrases. To correct them, one must find the sentence's real subject and rephrase the sentence so the subject is doing the action. For example,
Original: It is a shame that there is nothing we can do to help.
Rephrased:Our inability to help is a shame.
For more examples of expletives and how to correct them, please see the linked handout: