Study materials
A list reads easily when all its parts have the same form.
She enjoys reading, to write and painting.
Three different forms.
She enjoys reading, writing and painting.
Three matching forms.
This article explains parallel structure in a list and the paired conjunctions both … and, either … or, neither … nor, not only … but also.
Parallel parts
The items of a list have the same grammatical form: all with to, all in -ing, or all nouns.
The study aims to identify the cause, measuring the effect and an evaluation of the risks.
Three different forms.
The study aims to identify the cause, (to) measure the effect and (to) evaluate the risks.
Three matching forms.
The same holds for the paired conjunctions both … and, either … or, neither … nor, not only … but also. Each half is followed by the same form.
You can pay either by card or by transfer.
By and by.
The method is not only cheap but also fast.
Adjective and adjective.
If not only starts the sentence, inversion follows, that is, the helping verb comes before the subject: Not only is the method cheap, but it is also fast.
Common mistakes
The first mistake is different forms after not only and but also.
not only to reduce costs but also improving quality → not only to reduce costs but also to improve quality
Both halves match.
The second mistake is as well as after both.
both the students as well as the staff → both the students and the staff
Both takes and.
The third mistake is or after neither.
neither cheap or fast → neither cheap nor fast
Neither takes nor.
The first mistake shows when you compare the two halves of a paired conjunction. Each must be followed by the same form, here to with a verb. The second and third show in the second half of the pair. Both goes with and, either with or, neither with nor, and the pairs are not mixed.