In some contexts sentences that are grammatically incomplete are considered acceptable. For skilled writers, the brevity of certain sorts of incomplete sentence may make for an effective means of emphasizing a point or of indicating a change of direction:
In baseball, a lead of four runs going into the ninth inning is a safe lead. Not this time.
Is the original film better than the re-make? In every respect.
Contexts in which such writing may be considered appropriate occur far more frequently in informal writing than in formal writing—and instructors at the post secondary level often disagree as to when it is acceptable to deviate in this sort of way from grammatical conventions. For those reasons, students are well advised to consult their instructors before making a habit of intentionally writing sentence fragments for effect in formal academic writing.
The following exercise helps to give you a sense of the sorts of sentence fragments that are generally considered acceptable in informal writing (and that some may consider acceptable in certain sorts of formal academic writing as well).
Identify the sentence status of each of the following examples.
The children were in for a surprise. A big surprise.
The text in italics is
The children had just come into the house. When they were surprised by a clown carrying a bag of goodies.
Have the government’s efforts made a significant contribution to reducing poverty? Not so far as we can tell.
For most people, it takes a lot of hard work. To succeed at university.
It was a long time ago, and I can remember only one thing about her. Her perfume.
A bungled assassination attempt, and then a bit of very bad luck. That was how the First World War began.