Parallelism

When you write a list, every item does the same job, so every item must have the same form. A list of nouns stays a list of nouns. A list of gerunds stays a list of gerunds.

✔ Radhika likes reading, writing and swimming. (gerund, gerund, gerund)
✘ Radhika likes reading, writing and to swim. (use swimming)
✔ The new manager is polite, patient and helpful. (adjective, adjective, adjective)
✘ The new manager is polite, patient and with a helping nature. (use helpful)
✔ The guard checked every bag slowly and carefully. (adverb, adverb)
✘ The guard checked every bag slowly and with care. (use carefully)

One shared word is enough. If a little word such as his, the, a or to is going to be used with every item, either repeat it with every item or write it once at the start. Do not use it with one item and leave it out of another in a way that changes the pattern.

✔ He was praised for his honesty, his courage and his kindness.
✔ He was praised for his honesty, courage and kindness.

Keep the pattern inside each item as well. a great warrior and a very wise ruler both follow the pattern a + adjective + noun, so they match. Note that very goes with the positive degree, so a very wiser ruler is wrong.

> The last item of a list is the one the examiner changes, because it comes after and. When you see a list, jump to the word after and and compare it with the first item.

When two or more verb forms are joined, they must be the same form. There are three common cases.

1. Gerund with gerund.
✔ The doctor advised him to avoid eating sweets and drinking cold drinks.
✘ The doctor advised him to avoid eating sweets and to drink cold drinks.

2. Infinitive with infinitive. The sign to can be written with every verb, or once for the whole group. What you may not do is mix to + V1 with V1 + ing.
✔ The coach asked us to warm up, to stretch and to run two laps.
✘ The coach asked us to warm up, to stretch and running two laps.
✔ The need today is for both sides to introspect, re-examine the issue and resolve it amicably. (to is written once and shared by all three verbs)

3. Finite verbs in a row. When one subject does many actions, the verbs must be in the same tense and the same voice.
✔ Radhika opened the door, switched on the light and sat down.
✘ Radhika opened the door, switched on the light and sits down.
✘ The report was prepared by Radhika and submitted it on Friday. (passive, then active)

A second look at the pattern. If the first verb is followed by a gerund, check whether the next verb is a gerund too. In accused of accepting bribes and lied about it, the first verb after of is a gerund (accepting), so the second must be a gerund (lying).

✔ The politician was accused of accepting bribes and lying about it to the public.
✘ The politician was accused of accepting bribes and lied about it to the public.

> Parallel does not mean "same word". It means "same form". Accepting and lying are different words, but both are gerunds.

Not only … but also is the pair that the examiner uses most often, because it is easy to hide inside a long sentence. The concept is one line: whatever stands after not only and whatever stands after but also must have the same grammatical form.

✔ The policy was intended not only to streamline services but also to address complaints.
✘ The policy was intended not only to streamline services but also addressing complaints.

After not only we have to streamline, so after but also we need to address. The word addressing is a gerund and does not match.

Check the form. Different things can sit on the two sides, and each has its own matching form.

Check the place. Not only must stand just before the thing it joins.

✘ Radhika is not only beautiful but also has intelligence. (adjective on one side, a verb phrase on the other)
✔ Radhika is not only beautiful but also intelligent.
✘ Radhika not only is beautiful but also intelligent. (not only stands before the verb, but the other side has no verb)
✔ Radhika not only sings well but also dances well. (a verb on both sides)

Do not carry an extra word across. If a preposition belongs to both items, write it after both or before not only. Do not add it on one side only.

✘ It surprised not only the staff but also to the stakeholders.
✔ It surprised not only the staff but also the stakeholders.

Two small points. The partner of not only is but also. And also and but yet are wrong. When the pair joins two subjects, the verb agrees with the subject nearer to it, that is, the one after but also.

✘ Not only the manager but also his assistants was invited.
✔ Not only the manager but also his assistants were invited.

If not only begins the whole sentence with a helping verb (Not only did he fail …), only the first clause is inverted. The second clause keeps its normal order: but he also …. This is taught in the Inversion chapter.

These three pairs follow the same law as not only … but also: the thing after the first half and the thing after the second half must be the same in form, and the first half must stand just before its own item.

Where does the first half go? Look at what follows nor (or or). The first half must stand just before the same kind of word.

✘ The law aims to neither penalise small traders nor large firms.
✔ The law aims to penalise neither small traders nor large firms.

After nor comes a noun phrase (large firms), so neither must also stand before a noun phrase (small traders). Here neither was placed before the verb penalise, which left the two sides unequal. If the second side had a verb (nor to reward them), then neither would go before a verb: The law aims neither to penalise nor to reward small traders.

The correct partner. Neither goes with nor, either with or, and both with and. They must never be crossed.

✘ neither … or: ✔ neither … nor
✘ either … nor: ✔ either … or
✘ both … as well as: ✔ both … and
✘ both … and … and (three items): ✔ both … and (exactly two)

No second negative. Neither … nor already carries the negative, so not, never or no is not added in the same clause.

✘ He did not like neither the book nor the film.
✔ He liked neither the book nor the film.

Repeat the small word on both sides. If a preposition stands on one side, it stands on the other.
✘ His tone was neither of anger nor sorrow.
✔ His tone was neither of anger nor of sorrow.

Verb agreement. The verb agrees with the subject nearer to it: Neither the editor nor the contributors were willing … (the Subject-Verb Agreement chapter explains this).

Not … but sets one thing against another: it was not this, it was that. The two things must have the same shape, and that includes the little words in front of them: by, for, to, because, of, in.

✔ The theory was refuted not by logic but by emotion.
✘ The theory was refuted not by logic but emotion.

Not by logic begins with by, so the other side must also begin with by: but by emotion. If we leave out the second by, the sentence compares by logic with a bare noun, and the sides are no longer equal.

Same tense, same verb form. The two sides should also agree in tense when they are clauses.

✘ I declined the lunch offer, not because I do not want to go, but because I had no time.
✔ I declined the lunch offer, not because I did not want to go, but because I had no time.

The refusal is in the past, so both reasons are in the past: did not want and had.

Sense check. Not … but denies the first and affirms the second. If both are true, the writer would use not only … but also instead.

> A quick line to remember: if the first side opens with a little word, the second side opens with the same little word.

Sometimes one side of the pair is a noun phrase (the length of the report) and the other side is a clause that begins with that (that its data was wrong). A noun phrase and a clause are not the same shape, so the sentence is not parallel.

✘ What troubled us was not the length of the report but that its data was wrong.
✔ What troubled us was not the length of the report but the fact that its data was wrong.

The length of the report is a noun phrase, so the other side must be a noun phrase as well. We turn the clause into a noun phrase by putting the fact in front of it: the fact that its data was wrong.

So there are two correct ways to repair such a sentence.

✔ What troubled us was not the length of the report but the fact that its data was wrong. (noun phrase, noun phrase)
✔ What troubled us was not that the report was long but that its data was wrong. (clause, clause)

The bridge words. Besides the fact that, we can use the idea that, the belief that, the claim that and the possibility that. Choose the one that fits the meaning, but the pattern is the same: the clause needs a noun in front of it to stand next to a noun phrase.

✘ The extent to which the minister's statement came under criticism reflects not merely public dissatisfaction but also that the media has begun scrutinising political rhetoric.
✔ … reflects not merely public dissatisfaction but also the fact that the media has begun scrutinising political rhetoric.

> What troubled us and What surprised us most are noun clauses that act as the subject. The sentence says "the thing that troubled us was …". What stands after was should be one thing, either a noun phrase or a clause, and the not … but pair must keep that one thing the same on both sides.

Some pairs repeat their first word in the second half. The repeated word is what makes the two halves equal, so it must not be changed into a different word.

1. Whether … or whether. When whether introduces a full clause, the second clause is introduced by whether as well. If cannot take its place.

✔ Whether he will agree or whether he will refuse is unclear.
✘ Whether he will agree or if he will refuse is unclear.
✔ It remains unclear whether the board intends to implement the proposal or whether the statement was merely a strategic ploy.
✘ It remains unclear whether the board intends to implement the proposal or if the statement was merely a strategic ploy.

If the two choices share one subject, we can write one whether for both verbs: Whether he agrees or refuses is unclear. What we may not do is begin with whether and change to if.

2. Partly … partly. The words that follow each partly must be the same.

✔ The delay was partly due to rain and partly due to strikes.
✔ The delay was attributed partly to industry pressure and partly to legal ambiguity.
✘ The delay was attributed partly to industry pressure and partly due to legal ambiguity.

The first partly is followed by to industry pressure, so the second must be followed by to legal ambiguity. Attributed to and due to are two different patterns and cannot be mixed.

3. A few more pairs that repeat.

Between is followed by and, never by to or or: between Radhika and Meera. From is followed by to (or till / until for time): from Agra to Jaipur.

> The repeated first word (whether, partly, on the one hand) is the sign of the pair. If you see it once at the start, look for the same word at the second joint.

When we compare two things or choose between them, the two things must again be of the same kind. This is the last place where parallelism hides.

1. Prefer … to. We say prefer X to Y. Prefer never takes than.

✔ I prefer tea to coffee.
✘ I prefer tea than coffee.
✔ Radhika prefers walking to driving. (gerund, gerund)
✘ Radhika prefers walking to drive. (gerund, V1)
✔ They prefer going to their uncle's house to going to the park.

If you want to use a verb, write both as gerunds with to, or both as infinitives with rather than:

✔ I prefer travelling by train to travelling by bus.
✔ I prefer to travel by train rather than (to) travel by bus.
✘ I prefer travelling on train than travelling by bus.

2. Would rather … than. Would rather is followed by V1, and so is than.

✔ I would rather stay at home than go out in this rain.
✘ I would rather to stay at home than going out.

3. Rather than and instead of. After rather than we keep the same form as before it. After instead of we use a noun or a gerund.

✔ He chose to resign rather than apologise.
✔ She decided to walk rather than take a taxi.
✔ We should plan carefully instead of acting in a hurry.

4. Than. Whatever stands before than is matched by the same kind of thing after than.

✔ It is easier to say than to do.
✘ It is easier to say than doing.
✔ Walking is better than running.
✘ Walking is better than to run.

> Prefer takes to, never than. And the two things joined by to are of the same kind: noun to noun, gerund to gerund.