TL;DR:
Most SAT grammar questions test a small set of rules: sentence boundaries, agreement, apostrophes and transitions.
Name the rule the sentence needs before you read the choices, then match the choice to that rule.
Keep a short rule sheet in your log, and add an example each time a rule catches you out.
Grammar questions on the SAT feel like a long list of special cases until you notice they repeat. The same few ideas come back in different sentences: where one sentence ends, whether a verb agrees with its subject, when a word needs an apostrophe, and which transition word shows the relationship between two ideas. Learn those four, and most questions become a matter of spotting which one applies.
Sentence boundaries: where one idea ends
A sentence needs one complete idea. Two complete ideas joined only by a comma is a comma splice, and it is one of the most common errors in these questions. You can fix it three ways: use a full stop, use a semicolon when the two ideas are closely linked, or join them with a conjunction such as and, but or so after the comma.
Agreement: the subject decides the verb
The verb has to agree with its real subject, not with the noun closest to it. Phrases that come between the subject and the verb, such as of old maps or with the new students, are easy to skip over. Cover them with your finger and ask what the subject is.
Worked example: fixing a comma splice and a subject-verb agreement error
Here is a sentence with two errors, written for this article.
The sentence as written: The box of old maps are in the hall, the rangers kept them after the survey ended.
Find the subject: the box, not maps. The phrase of old maps sits between subject and verb and doesn't change the subject.
Check agreement: box is singular, so the verb must be is, not are. The error is a subject-verb agreement error.
Check the boundary: the box of old maps is one complete clause, and the rangers kept them after the survey ended is another complete clause. Two complete clauses joined only by a comma make a comma splice.
Choose a fix for the boundary: a full stop, a semicolon, or a conjunction after the comma. Here, both clauses are separate facts that belong together, so and works. A full stop after hall is also correct.
Rewrite: The box of old maps is in the hall, and the rangers kept them after the survey ended.
Count what you fixed: two errors, one verb change (are to is) and one boundary change (a comma to a comma plus and). Recheck the new sentence the same way. The subject is box, which is singular, so is is correct. The clause before and and the clause after it are both complete, so the joining is correct.
Apostrophes: its and it's
The most tested apostrophe rule is the difference between its and it's. It's is a contraction for it is or it has. Its is the possessive, like his or hers. A quick test: replace the word with it is. If the sentence still makes sense, use it's. If not, use its.
Possessive nouns follow a similar logic. A single owner gets an apostrophe before the s, as in the ranger's map. Several owners gets the apostrophe after the s, as in the rangers' maps.
Transitions: how two ideas connect
A transition word tells the reader how the next idea relates to the last one. However and but show contrast. Therefore and so show a result. For example and for instance introduce an example. Furthermore and also add to the idea. Choose the transition by naming the relationship first, such as contrast or result, and then find the word that matches.
Relationship | Typical transitions | Test question |
|---|---|---|
Contrast | however, but, although | Do the two ideas disagree? |
Result | therefore, so, as a result | Does the second idea follow from the first? |
Example | for example, for instance | Is the second sentence a case of the first? |
Addition | furthermore, also, in addition | Does the second idea add to the first? |
Mistakes to avoid
Fixing a sentence by ear. Name the rule first, then check the choice against it.
Matching the verb to the noun next to it. Find the real subject.
Reading the choices in a rush and picking the one that sounds smoothest. The smoothest choice can break a rule.
Treating every comma as a problem. A comma between a complete clause and a dependent phrase is often correct.
Your plan for this week
Build a rule sheet: On one page, write the four rules in your own words, each with one example sentence you wrote yourself.
Do a set of grammar questions: For each question, write the rule the sentence needs before you look at the choices.
Log the misses: For each miss, record which rule you missed, and add the sentence to your sheet as a model.
Redo the misses after a day: Cover your first answers and fix each sentence again from the rule sheet.
After a few sets, you will see that a handful of rules cover most of your errors. Spend your study time on those, and the rest of the grammar questions get much easier to read.
Frequently asked questions
Is a comma splice always wrong?
Yes, when a comma alone joins two complete clauses. A comma with a conjunction such as and or but is correct.
Why does the answer use the verb that sounds wrong?
Your ear is trained on speech, which can be loose about agreement. Trust the rule over the sound, and check the subject again.
Should I memorize the whole list of transitions?
No. Learn the relationships, such as contrast and result. The words follow from the relationship.
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