Find the head of the subject
In The collection of old maps is valuable, collection determines the verb. Maps belongs to the phrase of old maps. Removing that phrase temporarily leaves The collection is valuable, which makes the agreement easier to hear and analyze.
Contrast this with The maps in the collection are valuable. Here maps is the head and collection is inside the descriptive phrase. The closest noun to a blank is not automatically the subject. Locating the sentence's main subject and verb is more reliable than matching whatever noun you read last.
Check number and timeline separately
Each of the instruments requires calibration uses a singular verb because each is singular. The engineer and the technician are responsible names two people, so the compound subject is plural. A series of workshops is scheduled uses singular series despite the plural workshops.
A verb can match the subject but still be in the wrong tense. Yesterday, the committee approved the plan describes a completed past event. Approves and will approve do not match yesterday. Look for explicit time clues before deciding that a question is only about singular versus plural.
Attach an opening modifier to its performer
Walking into the gallery, Mina noticed a painting clearly assigns the walking to Mina. Walking into the gallery, the painting caught Mina's attention accidentally places the painting in the grammatical position of the walker. A plausible overall event does not repair a misplaced modifier.
The same check works for descriptions of objects. Designed for shallow water, the vessel approached the shore attaches designed to the vessel. Replacing the subject with the shoreline would say the shoreline was designed for shallow water. Ask who or what the opening phrase actually describes.
Keep ownership and grammatical form clear
Its marks possession: the device lost its connection. It's is a contraction of it is or it has. A regular plural such as architects gains a possessive apostrophe after the s when something belongs to those architects: the architects' design. A single architect instead takes architect's.
Parallel lists use matching grammatical structures. To measure, to record, and to interpret is a list of infinitives. Observation, measurement, and analysis is a list of nouns. Switching the last item to she analyzes changes the structure and interrupts the list.
When reviewing a missed question, classify the error as agreement, timeline, attachment, ownership, or parallel form. Those categories describe what to inspect next time. They are more useful than a general note that the correct answer sounded better.
Put the idea into practice.
Try eight original questions with explanations after each answer.
Practice this skill →References and further practice
References establish the test context. The examples and teaching explanations here are original. See our methodology for coverage and limitations.