When we are writing items in a series (lists), those items must be in the same grammatical form: singulars with singulars, plurals with plurals, passives with passives, and so on. This is called "parallelism." Parallelism makes it easier for us to communicate with each other through speaking and writing.
When writing a series, you cannot mix gerunds and infinitives. They all have to be gerunds, or they all have to be infinitives.
Gerund series
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Incorrect
In the summer, I love to go hiking (gerund), boating (gerund), and to go (infinitive) mountain biking. -
Correct
In the summer, I love to go hiking (gerund), boating (gerund), and mountain biking (gerund).
Infinitive series
When writing infinitive series, the word "to" usually only appears before the first item instead of every item.
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Incorrect
Jesse loves to read, to write, and to draw. -
Correct
Jesse loves to read, write, and draw.
However if a sentence is long, it is often best to include "to" before each infinitive phrase.
In his training for a kids helpline, David learned to listen attentively to other people, to be compassionate, and to put himself in other people's shoes.
More parallelism errors
Gerunds or gerund phrases containing a possessive or having + past participle must also be in parallel structure.
I want to thank everyone for making this party the best party I've ever attended! I especially appreciate Elaine's having sent everyone invitations, Jack's having cooked us the delicious food, and Jennifer's having organized this entire event all by herself!
Long infinitive phrases should similarly be presented in the same structure.
Applicants to the university are expected to have completed all respective provincial exams, to have obtained an A- standing on all core courses, and to have participated in relevant extracurricular activities.
Exercise
Open the exercise to begin the activity. Follow the instructions in the document.