Add "-ed" to the infinitive form of a regular verb that ends in a consonant to construct the preterite. The preterite of "walk" would be "walked," for example, and the preterite of "listen" would be "listened." Preterites of English verbs other than "to be" are identical for all persons; for example, "I walked" or "they walked" use the same form.
Add "-d" to the infinitive form of a regular verb that ends in "e" to construct the preterite. The preterite of "love" is "loved" and of "stroke" is "stroked."
Use the auxiliary verb "did," the negative "not" and the infinitive form of the verb to construct a negative preterite. To deny having walked in the past, you would say "I did not walk."
Note that many of the most common verbs in English, such as "say," "go," "be" and "leave," are irregular. Memorize conjugations for irregular verbs because they do not follow straightforward rules.
Form the preterite of strong verbs by changing the vowel. There are about 100 strong verbs in English that form preterites by changing vowels. The precise nature of the vowel change depends on which of the seven classes of Old English strong verbs the modern verb descended from.
Change the present tense of the strong verb "wake" to the preterite "woke," of "think" to the preterite "thought" and of "sing" to the preterite "sang".