~たり Representative Form

This verb form is used to express an action that is representative among many other possible actions.

• Group 1: Change the final る to たり
• Group 2: When the final syllable is
  く, change it to いたり
  ぐ, change it to いだり
  す, change it to したり
  む, ぬ, or ぶ, change it to んだり
  つ, る, or う, change it to ったり
  Exception: いく (to go) →いったり
• Group 3: くる→きたり、する→したり

This form is never used at the end of a sentence. The most common way to use this form is to link two or three たり-forms and end the sentence with the verb する（します for polite）. This construction expresses actions that stand out among many other possible ones. The sentence implies more actions than those explicitly mentioned.

あした		つく		か		もの		い
明日、	ケーキを	作	ったり、	買	い	物	に	行	ったりします。