Section I: Adding a Sentence

A paragraph is a chain of links: each sentence picks up something from the one before it and hands off something to the one after it. A sentence being added has its own hooks, often a pronoun like this, they, or such, or a transition like however or as a result. Those hooks need an antecedent or a setup, and only one gap in the paragraph supplies it. That's why a sentence can be completely true and completely on-topic and still only work in one place: truth and topic don't fix a gap, but reference does.

To test a candidate sentence, read the sentence right before the gap and ask what the new sentence's opening word or phrase would have to point to. Then read the sentence right after the gap and ask whether it still makes sense once the new sentence sits in front of it. Both checks have to pass. A sentence can sound smooth going in and still break the connection coming out, because inserting it changes what the following sentence is now reacting to. Skipping the second check is the most common way to pick a plausible-looking wrong gap.

This question type sits alongside the other writing questions on the student draft, where you're also asked to judge transitions, combine sentences, or cut weak ones. All of them test the same skill: tracing how one sentence depends on its neighbors rather than judging sentences in isolation. Getting comfortable with 'what does this word point to' pays off across that whole set of writing questions, not just this one.