Present, Future 大人っぽい is [x] 大人っぽくない is not [x] Past 大人っぽかった was [x] 大人っぽくなかった was not [x] Te-form, Continuative 大人っぽくて is [x] and... 大人っぽくなくて is not [x] and... Provisional 大人っぽければ if it is [x] 大人っぽくなければ if it is not [x] Conditional 大人っぽかったら when/if it is [x] 大人っぽくなかったら when/if it is not [x] Adverbial 大人っぽく [x]-ly Noun form 大人っぽさ [x]-ness