Sentence completions are not just pure vocabulary tests. To figure out the right answer, you have to decode the sentence to understand how it’s functioning. “Decoding a sentence” might sound difficult, but it’s something you do every day. For example, when you a hear a sentence such as “Usually I am happy, but . . .” you immediately know that the second half of the sentence will go something like “I am not happy right now.” On hearing the word “but” in relation to the initial statement, you realize that the second half will contradict the first half. This intuitive thought process is what we mean by decoding the sentence.

Let’s apply the decoding technique to the two examples above. In the one-word example about Bel Biv Devoe, there are no words like “but,” so the first and second part of the sentence must agree—if Bel Biv Devoe is a terrible singing group, then their lyrics must be poor. For the two-word example sentence about seals, you can decode it by realizing that the initial word, “though,” implies that the two halves of the sentence will oppose each other. In other words, what is true in the first half will be the opposite in the second half: though seals might lumber and look awkward on land, they move smoothly and gracefully in the water.

Think of a simple sentence. Actually, forget it. We’ll give you a simple sentence:

This sentence has a single flow or direction: it expresses a single idea from the beginning to the end. Now consider a variation of this sentence:

In this second sentence, there are two flows: the half of the sentence before the comma states a fact, and the half of the sentence after the comma states a different fact that is in opposition to the first. The flow of the sentence changed.

Now let’s say that the second sentence was an SAT sentence completion with, for the sake of simplicity, only two possible answers:

We already know that the answer is refused, but pretend for a moment that you don’t. How could you figure out the answer? We’ll answer this question by writing out a sentence in which began actually would make sense:

These two sentences differ by only two words: the first sentence begins with “though,” while the second sentence replaces the “though” with an “and” in the middle. The addition or subtraction of the “though” and the “and” completely change how the sentence functions. We call such words “hinge words” because, just as a hinge determines whether a door is open or closed, hinge words determine the flow of the sentence. The sentence about the scientists with the hinge word “though” is a contrasted sentence—there is a change of direction between the first and second halves. The second sentence with the hinge word “and” is a straight or direct sentence with a single flow.

As you can see, being able to identify hinge words is a vital part of decoding a sentence. You should also notice that there are two types of hinge words: those such as “and” that signal a sentence will continue in the same direction, and those like “though,” which signal that a sentence will change direction.

Identifying hinge words to help you determine the flow of the sentence is one of the best methods for answering sentence completions. Learning to identify hinge words should be one of your first tasks in preparing for the sentence-completion portion of the SATs.