American Diploma · Digital SAT · Grammar: Form, Structure and Sense

Parallel Structure

Keep matching forms in lists, paired conjunctions (both/and, either/or, neither/nor, not only/but also) and comparisons with than and as — rules, worked examples and a 10-question practice quiz.

American Diploma › Digital SAT Reading and Writing — Complete Course

What this question type tests

Parallel structure questions sit in Standard English Conventions, the grammar-and-punctuation domain of the Reading and Writing section (about 26% of the scored questions, usually 11–15 of them). The official skill list does not name parallelism as a separate skill, but it is part of writing sentences whose form and structure make sense — and it is often the quickest way to decide between verb forms such as create / creating / to create / the creation of. Grammar questions usually come after the reading questions in each module.

The stem is the usual one: "Which choice completes the text so that it conforms to the conventions of Standard English?" The blank is almost always the last item of a list, the second half of a pair (not only… but also…, either… or…), or the part after "than" or "as" in a comparison. The four choices show the same idea in four different grammatical forms. Your job: copy the form of the item that is already in the sentence.

The big idea: same job, same form

When two or more items do the same job in a sentence and are joined by and, or, but, a paired conjunction, or than/as, they must have the same grammatical form. Think of a list as a row of matching boxes: if the first box holds a verb, every box holds a verb.

If the first item is…	the others must be…	Example (✓)
a base verb	base verbs	The app lets students record lessons, share notes, and create quizzes.
an -ing form (gerund)	-ing forms	She enjoys reading, swimming, and painting.
an infinitive (to + verb)	infinitives	Our goals are to save water and to cut costs.
a noun / noun phrase	nouns / noun phrases	The kit includes a map, a compass, and a first-aid box.
an adjective	adjectives	The report was short, clear, and convincing.
a past verb	past verbs	The team collected samples, tested them, and published the results.
a clause (that…)	clauses (that…)	The study found that sleep improves memory and that naps help too.

Rule 1: Lists of two or three items

Find the first item, check its form, then make the blank match. Look carefully at the word that controls all the items ("lets students…", "must…", "is…"): every item must fit after that word.

✗ The app lets students record lessons, share notes, and the creation of quizzes.
✓ The app lets students record lessons, share notes, and create quizzes. (lets students record / share / create)
✗ A strong candidate must be honest, hard-working, and show patience.
✓ A strong candidate must be honest, hard-working, and patient. (be honest / hard-working / patient)
✗ The volunteers cleaned the beach, planting trees, and painted the fence.
✓ The volunteers cleaned the beach, planted trees, and painted the fence.
✗ The course teaches how to write emails, giving presentations, and the leading of meetings.
✓ The course teaches how to write emails, give presentations, and lead meetings.

The "to" rule: with a list of infinitives, either put "to" before every item or only before the first. Do not mix: "to measure, record and to file" ✗ → "to measure, to record and to file" ✓ or "to measure, record and file" ✓. The same idea works for other little words that start a list, such as prepositions: "in the morning, in the afternoon, and in the evening" or "in the morning, afternoon, and evening".

Hidden list: sometimes the items are long, so the list is hard to see. Strip each item down to its first word: "The new law requires companies to reduce packaging that cannot be recycled, to report their yearly waste figures to the ministry, and to pay…" — to reduce / to report / to pay.

Rule 2: Paired conjunctions

Some conjunctions come in pairs. Whatever comes right after the first word must match what comes right after the second word.

Pair	✓ Parallel	✗ Not parallel
both … and	both for its beauty and for its history	both for its beauty and its history was important
either … or	either call the office or send an email	either call the office or sending an email
neither … nor	neither cheap nor easy to repair	neither cheap nor could it be repaired easily
not only … but also	not only to protect reefs but also to support fishers	not only to protect reefs but also for supporting fishers
whether … or	whether by train or by bus	whether by train or taking the bus
not … but	not in Cairo but in Aswan	not in Cairo but the event was in Aswan

Also learn the correct partners. Either goes with or, neither with nor, not only with but also, both with and. "Neither… or" ✗, "both… as well as" ✗, "not only… and also" ✗ are all wrong pairings the test may offer.

Placement of the first word: "He either will call or email" ✗ (will call / email do not match) → "He will either call or email" ✓ (call / email).

Rule 3: Comparisons with than and as

A comparison is a pair too. The two things on each side of than or as… as must have the same form: -ing with -ing, infinitive with infinitive, noun with noun.

✗ Reading a map is harder than to use a phone app.
✓ Reading a map is harder than using a phone app.
✓ To read a map is harder than to use a phone app. (correct but more formal)
✗ Keeping customers is as important as to attract new ones.
✓ Keeping customers is as important as attracting new ones.
✗ Many students prefer studying in groups to study alone.
✓ Many students prefer studying in groups to studying alone. (prefer X to Y)
✓ She chose to walk rather than to wait for the bus. / She chose to walk rather than wait.

When the two sides of a comparison are things rather than actions ("the population of Cairo" vs "Alexandria"), the problem is a logical comparison. That is taught in the next lesson, Comparisons.

القاعدة في جملة واحدة

لو فيه قائمة أو حاجتين مربوطين بـ and / or / but أو not only … but also أو than، كل جزء لازم يبقى بنفس الشكل.
بص على أول عنصر: لو فعل يبقى الكل أفعال، لو ing يبقى الكل ing، لو to + فعل يبقى الكل to + فعل.
اللي بعد not only لازم يشبه اللي بعد but also، واللي قبل than لازم يشبه اللي بعدها.

The 3-step method for test day

Spot the signal. A list with commas + and/or, a paired conjunction, or than / as… as.
Find the partner. Underline the first item (or the item before than / after not only). Name its form: base verb, -ing, to + verb, noun, adjective, past verb or clause.
Match and check. Pick the choice with the same form, then read the whole sentence: the choice must also fit after the controlling word (must…, lets students…, is…). Reject choices that add a new subject and verb (they can…, it is…) inside the list.

Worked examples

Worked example 1: a list after a helping verb

Each spring, the city holds a fair where teenagers present their own inventions. To qualify for the fair, a project must solve a real local problem, use materials costing less than 500 pounds, and ______ by a team of no more than three students.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) be built
B) building
C) it is built
D) to be built

Answer: A) be built

The list follows "must": must solve…, (must) use…, and (must) be built. Each item is a base verb, so A keeps the list parallel.
B is wrong: "must building" is not a correct verb form, and it breaks the pattern.
C is wrong: "it is built" adds a new subject and verb inside the list, so the items no longer match.
D is wrong: "must to be built" — after "must" we never use "to".

Worked example 2: not only … but also

When the marine reserve in the Red Sea was opened, officials explained that it had more than one aim. The reserve was created not only to protect fragile coral reefs but also ______ that depend on healthy fish populations.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) for the support of local fishing communities
B) supporting local fishing communities
C) local fishing communities would be supported
D) to support local fishing communities

Answer: D) to support local fishing communities

After "not only" comes "to protect" (an infinitive), so after "but also" we need "to support" (D).
A is wrong: "for the support of" is a prepositional phrase, not an infinitive.
B is wrong: "supporting" is an -ing form; it does not match "to protect".
C is wrong: it is a full clause with its own subject, so the two halves no longer match.

Worked example 3: a comparison with than

Music teachers at a Cairo conservatory surveyed their beginner students about their first year of lessons. For most beginners, learning to read music turned out to be harder than ______ simple songs by ear.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) to play
B) playing
C) they played
D) the playing of

Answer: B) playing

The subject is "learning" (an -ing form), so the other side of "than" must also be an -ing form: "learning… is harder than playing…" (B).
A is wrong: "to play" is an infinitive; it does not match "learning".
C is wrong: "they played" is a clause, not an action that matches "learning", and the sentence becomes illogical.
D is wrong: "the playing of simple songs" is a wordy noun phrase that breaks the -ing/-ing match.

Worked example 4: either … or

Visitors to the Wadi El Gemal reserve have two ways to explore its coastline. They can either ______ or join a guided boat tour that leaves the harbor every morning.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) hike the coastal trail on their own
B) hiking the coastal trail on their own
C) a hike along the coastal trail on their own
D) to hike the coastal trail on their own

Answer: A) hike the coastal trail on their own

"Can either ___ or join" — after "or" comes the base verb "join", so after "either" we need a base verb too: "hike" (A). Both also fit after "can".
B is wrong: "can hiking" is not a correct verb form, and -ing does not match "join".
C is wrong: "a hike" is a noun phrase; it does not match the verb "join".
D is wrong: "can to hike" — after "can" we never use "to".

Classic traps

The last-item switch: the first items are verbs, the last one becomes a noun phrase ("and the creation of…") or an -ing form.
The new-clause trap: the last item adds its own subject and verb ("and they can create…", "and it is built…").
The wordy noun trap: "the + noun + of" choices (the leading of meetings, the support of) sound formal but break the pattern.
The wrong partner: neither… or, not only… and also, both… as well as.
The than/as mismatch: -ing on one side, to + verb on the other ("Reading is harder than to write").
The half-repeated "to": to measure, record and to file — all or only the first.

Fast strategy for test day

When the four choices are the same verb in four forms (create / creating / to create / the creation of), look for a list, a pair or than/as.
Look back at the first item, not at the item just before the blank — but check both.
Read the controlling word plus your choice ("must be built", "lets visitors create") to make sure it fits.
The shortest choice that matches the pattern is usually right.
Do not confuse this with list punctuation: here the commas are already fixed; only the form of the words changes.

خلي بالك من الفخ ده

الاختيار الغلط غالبًا بيبان «رسمي» وطويل زي the creation of أو they can create. ده بيكسر الشكل. ارجع لأول عنصر في القائمة واختار نفس الشكل بالظبط، وغالبًا الإجابة الصح هي الأقصر.

Practice

Remember

Items in a list must have the same form: verb–verb–verb, -ing–-ing–-ing, noun–noun–noun.
In a pair, what follows the first word must match what follows the second: not only to X but also to Y.
Use the right partners: either/or, neither/nor, both/and, not only/but also.
Both sides of than or as… as must match: reading is harder than writing.
Reject choices that start a new clause (they can…, it is…) inside a list.

All pages in this course

Start here

Craft and Structure

Information and Ideas

Standard English Conventions

Expression of Ideas

Full practice tests