Present, Future 役立つ, 役立ちます [does], will [do] 役立たない, 役立ちません doesn't [do], will not [do] Past 役立った, 役立ちました [did] 役立たなかった, 役立ちませんでした didn't [do] Te-form, Continuative 役立って, 役立ちまして 役立たないで, 役立ちませんで 役立たなくて Progressive 役立っている, 役立っています [doing], to be [doing] 役立っていない, 役立っていません not [doing] Volitional 役立とう, 役立ちましょう let's [do]!, I/we will [do], I/we intend to [do] 役立つまい, 役立ちますまい I will not [do], I do not intend to [do] Imperative 役立て, 役立ちなさい [do] ! 役立つな, 役立ちなさるな don't [do] ! Request 役立ってください please [do] 役立たないでください please don't [do] Provisional 役立てば if X [does], if X [is ~] 役立たなければ if X doesn't [do], if X [is not ~] Conditional 役立ったら, 役立ちましたら if X were to [do], when X [does] 役立たなかったら, 役立ちませんでしたら if X weren't to [do], when X doesn't [do] Potential 役立てる, 役立てます be able to [do], can [do] 役立てない, 役立てません not be able to [do], can't [do] Passive, Respectful 役立たれる, 役立たれます is [done] (by ...), will be [done] (by ...) 役立たれない, 役立たれません isn't [done] (by ...), will not be [done] (by ...) Causative 役立たせる, 役立たせます makes/will make (someone) [do] 役立たせない, 役立たせません doesn't/won't make (someone) [do] Causative passive 役立たせられる, 役立たせられます is made/will be made to [do] (by someone) 役立たせられない, 役立たせられません isn't made/won't be made to [do] (by someone) ~たい form 役立ちたい want to [do] 役立ちたくない don't want to [do]