However, it sometimes translates to the verb ‘to be’, or it is found in expressions where completely different verbs are used in English. Common expressions using avoir include: ...

So, in IKIMASU (to go), you change KI to KU, and get IKU. There are two irregular verbs that don’t fit the above patterns. They are KIMASU (to come), and SHIMASU (to do). KIMASU becomes KURU ...