Why this matters on the SAT
On the SAT, the four choices are often forms of the same verb, such as convert, converting, to convert and having converted. Each form does a different job, and only convert can be a sentence's main verb on its own. When the choices look like these, the question underneath is always the same: does the sentence still need its main verb? Count the main verbs, and most of these questions are settled.
Solution to the example
The subject of the second sentence is These structures, and no word yet says what they do: helping to power growth and repair only describes. So the blank has to be the main verb, and only convert can be one. The answer is D. A, B and C can't be a main verb on their own (the next section shows why), so they'd leave a fragment. A tempts most, because it echoes helping.
SAT example
Under a microscope, a cell’s mitochondria may look like tiny beans. These structures _____ energy from nutrients into a form the cell can use, helping to power growth and repair.
Which choice completes the text so that it conforms to the conventions of Standard English?
converting
to convert
having converted
convert
A complete sentence needs a subject and a main verb: who or what the sentence is about, and the verb that says what the subject does or is. It also needs no word, like because or when, that makes it lean on another sentence. Words that pass all three checks can stand alone. Grammar books call them an independent clause; this course calls a complete sentence a full sentence. Words that can't stand alone but are punctuated as a sentence are a fragment.
In the examples, the subject and main verb, or the word that makes the words lean, are underlined.
The first fragment has no subject: who loads the trucks? In the second, because makes the words wait for more.
A verb comes in several forms, and only some of them can be a sentence's main verb. An -ing form, a to form and a having form can't, on their own.
| Can be the main verb | Can't be the main verb on its own |
|---|---|
| loads, loaded, has loaded, will load, is loading | loading, to load, having loaded |
| is, are, was, were | being, to be, having been |
Grammar books call a main-verb form finite and an -ing, to or having form nonfinite. You won't need the terms again. In the examples, the words that change are bold.
The wrong version sounds close to right, because the night crew loading the trucks is a fine way to start a sentence. But nothing says what the crew does. An -ing word needs a helper before it can be a main verb: loading → is loading. A to form or a having form never can be.
The form that usually tempts most is being, because it sounds conversational, but it's never a main verb on its own.
Fragment or complete sentence? The bakery on the corner being the oldest shop on the street.
On this SAT question, find the subject, then ask whether any word yet says what it is or does.
Practice problem
Many people think that moss only grows on the north side of trees. In reality, moss ______ able to grow on any side that stays damp and shaded.
Which choice completes the text so that it conforms to the conventions of Standard English?
SAT sentences are long, and many of their verbs aren't the main one. A verb inside extra information, or inside a clause that starts with a word like because, when, although, which, that or who, belongs to that part, not to the sentence. To find the main verb, cross out the extra information between commas or dashes, set those clauses aside, and read all the way to the period.
In these examples, the crossed-out words are what you remove, and the subject and main verb are underlined.
The trap: a sentence can be full of verbs and still be a fragment.
Sometimes the subject itself is an -ing phrase or a clause, with verbs of its own. Before you call the words a fragment, look past them for a main verb. If one comes later, put what in front of it and ask. When the answer is the whole phrase or clause, it's the verb's subject.
What takes the crew ten minutes? Checking whether every truck is full, the whole phrase. Is belongs to the whether clause inside it.
In this question, set the because clause aside, then read past a long subject and ask whether anything yet is its main verb.
Practice problem
Because neurons in the enteric nervous system respond to chemical and mechanical signals from the digestive tract, determining whether a particular intestinal contraction was initiated locally or directed by the brain through the vagus nerve _____ researchers to record both neural pathways simultaneously.
Which choice completes the text so that it conforms to the conventions of Standard English?
Now the other direction, the more common one on the test. When the sentence already has its main verb, the blank can't add another one. It only describes, with a form that isn't a main verb, most often an -ing form. Two cases change that, and the next section covers both: a blank in a clause of its own, and a blank in a list of actions joined by a word like “and”.
The describing form can follow the full sentence. In these examples, the main verb already in the sentence is underlined.
Left would be a second main verb for crew, with no “and” to join it to loaded.
The main verb can also come after the blank. Then the blank sits between the subject and its main verb, and describes the subject.
Loads sounds right until you reach finishes. The main verb can come after the blank, so read to the period before you decide.
One of the hardest versions puts a new noun before the blank, with no joining word such as “and” in front of it. After a full sentence and a comma, a noun with a word that only describes it can add a detail. A main verb there would make a second full sentence, and a comma alone can't join two full sentences. That error is a comma splice, the subject of Joining two sentences.
The warehouse empty at last has no main verb, so the comma attaches it. Grammar books call this an absolute phrase. It often starts with a word like its, their or each, right after the comma.
The describing form can also open the sentence, before the subject, or follow with and a noun. Either way, the sentence's main verb is somewhere else.
After with and a noun, the verb form only describes, never a main verb: finished is the sentence's main verb, and waiting only describes the drivers.
That makes the test a count. No main verb yet: the blank is the main verb. One already: the blank only describes, unless it's in a clause of its own or a list, the two cases the next section covers.
Carries or carrying? The ferry ______ the island’s only doctor docks twice a day.
To tell whether an -ed form is a main verb or only describes, use the was test: put was or were in front of it. If the result says what the sentence means, that something was done to the noun, the -ed form only describes.
But the crew loaded the trucks → the crew was loaded the trucks makes no sense: the crew did the loading. An -ed form that fails the was test is a main verb, so in a sentence that already has one, outside a clause of its own or a list, it's a second main verb.
Once in a while, the choices hold two describing forms. Take -ing if the noun does the action and -ed if something is done to it.
Run the count on this SAT question: cross out the extra information, read to the period, and put any -ed form through the was test.
Practice problem
Marine archaeologists _____ the durability of ancient Roman harbor concrete, which has remained intact for nearly two millennia despite constant exposure to seawater, have identified a chemical reaction between volcanic ash and seawater that can strengthen the material over time.
Which choice completes the text so that it conforms to the conventions of Standard English?
Two cases let the blank be a main verb even when the sentence already has one. The first: every clause needs its own main verb. A clause is a subject with its verb, and one sentence can hold several. So find the blank's own subject. If it's which, that, who or a whose phrase (whose work), or a new subject after a word like that, how, because or a joining word (“and”, “but”, “so”…), the blank is in a clause of its own. If that clause has no main verb yet, the blank is its main verb. In these examples, the words that open the clause are underlined.
The drivers is a new subject after “and” or that, so it needs a main verb of its own. In the last three, one word changes the job: with that, the words after trucks are a clause and need a main verb; without it, they only describe the trucks. Before you decide the blank only describes, find the blank's own subject.
Extra information can sit between the blank's subject and the blank. Cross it out first.
Speaks or speaking? The museum hired a guide who ______ four languages.
The second case is a list. When the blank is an item in a list of actions joined by “and”, it takes the same form as the other items, even if that makes it another main verb.
Here the count alone would mislead you: the sentence already has sorted and loaded. But “and” makes the blank the third item in the list, and a joining word like “and” lets one subject take more than one main verb.
The same goes for a pair, and for describing forms: items joined by a word like “and”, “but” or “or” match.
On this SAT question, count the main verbs, then look around the blank for a list before you pick.
Practice problem
In preparation for a touring production of A Midsummer Night’s Dream, costume designer Lila Chen fitted each actor during tech week, labeled every garment for the backstage crew, and ____ notes about repairs that could be done between cities.
Which choice completes the text so that it conforms to the conventions of Standard English?
When the sentence already has its main verb, the blank is often a to form instead of an -ing form. A to form can say why an action happens. To check, put in order in front of it: if that fits, the to form does.
But only an action done for a reason can have a purpose, and a pipe doesn't burst for one:
Flooding the warehouse floor says what the burst did, so it takes -ing.
Some words also take a to form right after them, with no purpose involved: decided, need, plan, able, the first, a way.
When no word before the blank calls for a to form, the to form has to pass the in order test.
In this question, find the main verb first, then try in order in front of the to form.
Practice problem
Some bacteria are nearly transparent when viewed through a microscope. Microbiologists often apply colorful dyes to the bacteria ______ details in the cells more clearly.
Which choice completes the text so that it conforms to the conventions of Standard English?
Here's the move that makes these questions fast. Before you read the sentence closely, sort the choices into two groups: forms that can be the main verb, and forms that can't. The opening question's choices sort like this:
The sentence decides which group the answer is in. If the blank needs a main verb, the second group goes at once; if it doesn't, the first group does.
That makes one routine for every verb-form question, the one the worked examples and the final practice problems follow:
Run the count on six short sentences before the worked examples. For each one, decide whether the blank needs a main verb, then check your answer.
Opens or opening? The bakery on Front Street ______ at six every morning.
Rises or rising? The bread ______ in the warm back room is ready by noon.
Draws or drawing? The new exhibit opened on Friday, ______ a long line of visitors by noon.
Repair or repairing? The mechanics who ______ the ferry’s engines work through the night.
Painted or were painted? The murals ______ by local students line the school’s front hall.
Checks or checking? Each morning, the guide unlocks the gallery, ______ the lights, and greets the first visitors.
In this question, the subject and its main verb sit about forty words apart, with other verbs in between.
Worked example
Musicologist Priya Nwosu's searchable catalog of early field recordings, many of which had previously been attributed only to unnamed singers, _____ regional variations in tempo and ornamentation that older inventories overlooked and thereby giving historians a more precise basis for tracing musical exchange, has transformed research on performances preserved on wax cylinders.
Which choice completes the text so that it conforms to the conventions of Standard English?
revealed
has revealed
reveals
revealing
Step 1
The choices are four forms of reveal. Has revealed and reveals can only be main verbs, revealing can't be one, and revealed could be either, so the was test will place it. The question is whether the sentence still needs its main verb.
The subject is the catalog of early field recordings. Right after it comes extra information between commas, many of which had previously been attributed only to unnamed singers, and its verb, had been attributed, belongs to which. Cross it out.
Step 2
Keep reading past the blank. Overlooked belongs to the that clause, that older inventories overlooked, and thereby giving only describes. Then, near the period: has transformed research. What has transformed research? The catalog. That's the main verb.
The sentence already has its main verb, so the blank only describes. That rules out C and B: each would give the catalog a second main verb. C tempts most, because right after the extra information, reveals reads like the main verb, until you reach has transformed.
Step 3
Revealed might look like a describing form, so test it: the catalog was revealed regional variations makes no sense. The catalog does the revealing, and regional variations is what it reveals. So revealed can only be a main verb here, a second one, and A goes too.
Step 4
The catalog does the revealing, so the -ing form fits, and it matches the -ing form joined to it by “and”: revealing … and thereby giving. The answer is D.
Here three choices are main-verb forms, and the words after the last comma look like the start of a new sentence.
Worked example
In the 1960s, neuroscientists Ronald Melzack and Patrick Wall argued that pain signals can be amplified or dampened in the spinal cord rather than transmitted unchanged to the brain. The theory was initially met with skepticism, but it is now a cornerstone of pain research, its influence ______ in everything from physical therapy protocols to virtual reality treatments.
Which choice completes the text so that it conforms to the conventions of Standard English?
is evident
was evident
evident
had been evident
Step 1
Is evident, was evident and had been evident are main-verb forms; evident alone is a describing word, not a verb. So the question is whether the words after the last comma, its influence ______ in everything…, need a main verb.
Step 2
The second sentence joins two full sentences with a comma and “but”, and the second of them, it is now a cornerstone of pain research, has it and is as its subject and main verb. Nothing opens a clause of its own for the blank: no word like that, how, because or a joining word comes right before its influence. There's no list either. So the sentence already has its main verb, and the blank only describes.
Step 3
Its influence looks like a subject waiting for its verb, and is evident is what you'd write if those words stood alone. That's why A tempts most. But with is evident, the words after the comma become a second full sentence, and a comma alone can't join two full sentences. A is a comma splice, and B and D make the same splice.
Step 4
Its influence evident in everything… has no main verb. It can't stand alone, so the comma attaches it, and it describes how far the theory now reaches: a noun with a describing word, like the warehouse empty at last. The answer is C.
These four questions mix the cases, so run the whole routine on each one: sort the choices, count the main verbs, then pick.
Practice problem
During an update to a popular photo-editing app, a small coding error deleted users’ saved preset filters, thereby _____ thousands of people to recreate their custom looks from scratch.
Which choice completes the text so that it conforms to the conventions of Standard English?
Practice problem
While cataloging pottery recovered from an ancient harbor, archaeologists found traces of grape pollen and pine resin inside several storage jars. The team's report _____ that the jars held locally produced wine rather than imported wine has prompted historians to reconsider the harbor's role in regional trade.
Which choice completes the text so that it conforms to the conventions of Standard English?
Practice problem
Glaciologists have learned that when meltwater streams enter a glacier through vertical shafts called moulins, they can reach the bedrock within minutes. There the water lubricates the ice–rock interface, increasing the glacier’s speed; it can also carve channels that, during periods of high flow, ______ excess water away from the bed and slow the glacier again.
Which choice completes the text so that it conforms to the conventions of Standard English?
Practice problem
In Gothic fiction, an ancestral mansion often functions not merely as a setting but as a record of concealed wrongdoing, each of its sealed rooms ______ evidence that the living characters would prefer to ignore.
Which choice completes the text so that it conforms to the conventions of Standard English?
Finish the lesson
Finish the remaining questions correctly to complete this lesson.
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