Three groups? Hmm.... I always thought that (for conjugation) there were 2 groups: Ru verbs and U verbs..... But, not all verbs that end in "ru" are Ru verbs. Only verbs that end in "iru" or "eru" (like "okiru" and "taberu").... And, there are still a few exceptions.... (Aren't there always!) For plain form: Present is just the verb, with no changes (I think....). "taberu" and "Kau" Past is a little lengthy to explain.... http://www.guidetojapanese.org/pastverb.html Negative: drop "Ru"(for Ru verbs) "U" (for U verbs, then add "A" row hiragana chart sound) and add "nai". Tabenai and Kawanai (verbs that end in only "U" are slightly irregular, as they drop the "U", and add "Wa", while other "U" verbs only drop the "U" and add the "A". (Ku--> Ka. Yaku --> Yakanai.) Stem: Drop Ru (for Ru verbs), or "U" (for U verbs, then add "I" row hiragana chart sound (AKA: Change the "U" to an "I"-- Ex. Hanasu --> Hanashi). "Tabe" and "Kai" (I think..... ^-^*) Te: Add "Te" to stem form. Tabete and Katte (Thank you Jamie! ^.^) If you need help with more polite and formal forms, (or if I've made this explanation too confusing...), please send me a message! ^-^ I hope I've helped! ^-^ BTW, please let me know what three groups you've learned to divide verbs into... It might help me help other people...... Plus, then I can change the form of my answer to better help you..... http://www.learnjapanesefree.com/basic-verb-forms-in-japanese.html http://www.guidetojapanese.org/learn/grammar#contents http://www.all-about-teaching-english-in-japan.com/Japanesegrammar.html http://en.wikipedia.org/wiki/Japanese_verb_conjugations_and_adjective_declensions If you're looking for a beginner's book for learning Japanese, I suggest "Japanese for Dummies"... I still find it useful.

James is right, just google this question or grab a grammar book. It is too difficult to explain everything here. The best way to learn is to sit down with the hiragana table and look for patterns in how the verbs change. @megumi - te form of kau is katte btw Also not all verbs ending in iru/eru are ru verbs. What about shaberu, siru, suberu etc?　(^_^)'

Do you have any examples?

This is a big question. Maybe you should consult a grammer book or look for the answer on Japanese-learning websites?