gerund and infinitive
How the gerund and the infinitive function in a sentence.
A gerund is the -ing form of a verb used as a noun. An infinitive is the base form of a verb, usually preceded by to, the infinitive marker. The infinitive can function as a noun, an adjective, or an adverb. As nouns, both serve as subjects, objects, and complements (Sanding the floors is noisy work; The board chose to adjourn). As an adjective, an infinitive modifies a noun (a form to sign). As an adverb, it modifies a verb or an adjective (She left early to catch the ferry; The rule is easy to follow).
A gerund phrase used as a subject is singular, whatever the number of the noun inside it: Grading the essays takes all weekend. Two gerunds joined by and that name separate activities take a plural verb: Cooking and cleaning are both on the schedule.
To is either the infinitive marker or a preposition. As a preposition, it takes a noun or a gerund as its object, never the base form of a verb. Many writers mistake the preposition for the infinitive marker in phrases such as look forward to and committed to. In these phrases the verb takes the gerund: The district is committed to hiring local teachers.
Every item in a series takes the same form: all gerunds (The job involves scheduling crews, ordering materials, and billing clients) or all infinitives. In a series of infinitives, put to before the first item only (to strip, prime, and paint the trim) or before every item (to strip, to prime, and to paint the trim), never before some items and not others.
A gerund or infinitive phrase that opens a sentence has no subject of its own, so readers take the subject of the main clause as the one performing the action in the phrase. When that subject cannot perform the action, the phrase is a dangling modifier. By checking the log, the fault was found says the fault did the checking, and To qualify for the rebate, the form must arrive by May 1 says the form is qualifying. Make the doer the subject: By checking the log, the technician found the fault; To qualify for the rebate, customers must file the form by May 1.
See also gerund / present participle; possessive before a gerund; dangling modifier.
Examples
UseLucas admitted to forging the signature. (To is a preposition here, so its object is the gerund forging.)
UseThe plan is to lease a second truck, add two welders, and bid on the county contract. (One to governs all three infinitives.)
UseTo beat the traffic, we left before dawn. (The subject, we, is the one beating the traffic.)
AvoidCleaning the gutters were the last chore on the list. (Were is the error: the subject is the gerund phrase Cleaning the gutters, which is singular. Write Cleaning the gutters was the last chore on the list.)
AvoidThe new owners are dedicated to keep the bakery open. (Keep is the error: the to after dedicated is a preposition, which takes a gerund. Write The new owners are dedicated to keeping the bakery open.)
AvoidHer duties include answering the phones, to greet visitors, and sorting the mail. (To greet is the error: the other items in the series are gerunds, so this one must be too. Write Her duties include answering the phones, greeting visitors, and sorting the mail.)
AvoidAfter sealing the envelope, the check was still on the desk. (After sealing the envelope is the error: the phrase has no subject of its own, so it says the check sealed the envelope. Write After sealing the envelope, I noticed the check still on the desk.)