How do you determine if a verb is a gerund?

Answer 1

This is a tricky one because verbs ending in -ing can either be a gerund or a present participle.

To give a better understanding, if the verb ending in -ing is more like a noun, it is usually a gerund. Ex) Fishing is fun.

If the verb ending in -ing is more like a verb or an adjective, it is usually a present participle. Ex) Anthony is fishing.

Reference: http:/www.englishclub.com/grammar/verbs-gerunds.htm

Answer 2

A gerund is a verb form that functions as a noun by adding the -ing suffix (e.g., "writing" in "I enjoy writing"). To determine if a verb is a gerund, check if it is used as a subject, object, or complement in a sentence, rather than as an action verb.