Perfect tense of strong (irregular) verbs How many of these past tense sentences do you understand? Note that the past participles of strong verbs end with -en (the weak verbs end with -t). Notice also that there can be a vowel change when putting the verb in the past tense - you will need to learn these changes. Activity created by R. Lloyd. Tools See a list of terms used in this activity. This activity was created by a Quia Web subscriber. To learn how to make your own, just like this, click here.