Parallel Structure

Parallel structure (or parallelism) means that ideas doing the same job in a sentence wear the same grammatical clothes. If the first item in a list is a noun, the rest should be nouns; if the first is an -ing verb, the rest should be -ing verbs. The CSE tests parallelism heavily in error-identification and sentence-correction items because broken parallelism is the classic mark of careless writing, exactly what a civil servant drafting memos must avoid. The good news: once you learn to line the items up in a column, these questions become some of the fastest points on the exam.

The core rule: match the forms

Whenever a sentence coordinates two or more elements with and, or, or but, or lists them with commas, put every element in the same form.

Broken	Parallel
The job requires encoding data, filing records, and to answer calls.	The job requires encoding data, filing records, and answering calls.
The seminar was informative, engaging, and it did not cost much.	The seminar was informative, engaging, and inexpensive.
Applicants must submit a resume, a diploma, and bringing two IDs.	Applicants must submit a resume, a diploma, and two valid IDs.
The memo explains what to file, where to file it, and the deadline.	The memo explains what to file, where to file it, and when to file it.

The test is mechanical. Write the list as a column and check that each item starts the same way:

• encoding data
• filing records
• to answer calls <- breaks the pattern

Worked example 1. Find the error: "The new HR officer is known for her patience, being diligent, and honesty." Column check: patience (noun), being diligent (-ing phrase), honesty (noun). The middle item breaks the noun pattern. Corrected: "her patience, diligence, and honesty."

Parallelism with verbs: watch the helpers

When list items share a helping verb, either repeat the helper for every item or state it once and drop it everywhere else. Mixing the two patterns is an error.

• Parallel: "The committee will review the bids, rank the suppliers, and award the contract."
• Also parallel: "The committee will review the bids, will rank the suppliers, and will award the contract."
• Broken: "The committee will review the bids, rank the suppliers, and will award the contract."

The same goes for to in infinitive lists: "to plan, to organize, and to lead" or "to plan, organize, and lead," but not "to plan, organize, and to lead."

Correlative pairs: the strict couples

Correlative conjunctions come in pairs, and the grammar after the first half must mirror the grammar after the second half exactly.

Pair	Rule and example
not only ... but also	Not only the staff but also the director attended. / She is not only smart but also hardworking.
either ... or	You may either email the form or submit it in person.
neither ... nor	The office accepts neither cash nor checks after 3 p.m.
both ... and	The policy covers both regular employees and job-order workers.
whether ... or	Decide whether to appeal or to comply.

The most common trick is a misplaced first half. In "She not only drafted the memo but also the report," what follows not only is a verb (drafted) while what follows but also is a noun (the report). Fix it by moving not only: "She drafted not only the memo but also the report."

Worked example 2. Which sentence is correct? (a) The training will either be held in Baguio or in Tagaytay. (b) The training will be held either in Baguio or in Tagaytay. (c) The training either will be held in Baguio or Tagaytay. (d) Either the training will be held in Baguio or Tagaytay. Line up what follows each half. In (b), either is followed by "in Baguio" and or by "in Tagaytay": two matching prepositional phrases. Answer: (b).

A bonus rule for subject-verb agreement: with either...or and neither...nor subjects, the verb agrees with the nearer subject: "Neither the chief nor the clerks were informed," but "Neither the clerks nor the chief was informed."

Parallel comparisons

Comparisons with than, as...as, and prefer...to must compare matching forms and logically comparable things.

• Broken: "Reviewing daily is better than to cram." Parallel: "Reviewing daily is better than cramming."
• Broken: "The fees in Quezon City are higher than Makati." Parallel: "...higher than those in Makati."
• Broken: "She likes fieldwork more than doing desk work... " Prefer matching: "She likes doing fieldwork more than doing desk work" or "She likes fieldwork more than desk work."

Worked example 3. Choose the correct sentence. (a) Walking to the office is healthier than to ride a jeepney. (b) To walk to the office is healthier than riding a jeepney. (c) Walking to the office is healthier than riding a jeepney. (d) Walking to the office is more healthy than to ride in a jeepney. Both sides of than must match: walking...riding. Answer: (c).

Parallelism beyond the sentence

Lists in memos, bullet points, and exam answer choices follow the same rule. If a series of duties begins with action verbs ("Prepare the agenda, Record the minutes"), every bullet should begin with an action verb, not switch to "Preparation of reports." The CSE occasionally embeds this in a "which does not belong" or best-revision item, so practice hearing the pattern: verb-verb-verb, noun-noun-noun, clause-clause-clause.

Parallelism also matters with paired clauses: "The supervisor explained how the system works and why it sometimes fails" (two how/why clauses), not "...and the reasons of its failure."

Worked example 4. Find the error: "The orientation covered how to file a leave application, how to request a service record, and the procedure for claiming overtime pay." The first two items are how-to clauses; the third is a noun phrase. Corrected: "...and how to claim overtime pay."

Common traps

• The hidden third item: in long sentences, the first two items are parallel and the break hides in the last item after and. Always check the final element first; that is where examiners plant the error.
• Mixed gerund and infinitive: "She enjoys reading and to travel" should be "reading and traveling." Remember that some verbs require one form (enjoy + -ing, decide + to), so the controlling verb sets the pattern.
• Half-repeated helpers: repeating will, to, or has for some items but not all.
• Correlative halves in the wrong spot: not only/but also, either/or must be placed immediately before the parallel elements.
• Unbalanced voice: "The plan was drafted by the team and the director approved it" mixes passive and active; smoother: "The team drafted the plan, and the director approved it."
• Faulty comparison targets: comparing a thing to a place or a person to an object ("Her workload is heavier than her officemate" should be "than her officemate's" or "than that of her officemate").
• Absent second as: "The annex is as big, if not bigger than, the main building" needs "as big as, if not bigger than, the main building."

Exam strategy

1. Whenever you see and, or, but, or a comma series in an underlined portion, run the column test: list the items vertically and compare their first words.
2. For correlative pairs, put your finger on the word right after each half; the two words must be the same part of speech or the same kind of phrase.
3. For than and as comparisons, name the two things being compared. If they are not the same type of thing (speed vs. office, workload vs. person), the item is testing faulty comparison.
4. In sentence-correction items, when two choices are both grammatical, the parallel one wins; the CSE treats parallelism as part of correctness and style.
5. Do not "fix" a sentence that is already parallel in a less obvious way; "to plan, organize, and lead" is correct even though to is not repeated.

Parallelism is pattern-matching, not memorization. Train your eye to stack coordinated items in a column, and the broken piece will stand out like a bent railing.