The past participle is used extensively in Yiddish. The majority of verbs (so-called weak verbs) form the past participle by adding the prefix -גע "ge-" and the suffix ט- "-t" to the stem, e.g. געקויפֿט "gekoyft" 'bought'. However, strong verbs form the past participle with -גע and ן- "-n", usually accompanied by a vowel change, e. g. געהאָלפֿן "geholfn" 'helped' from the stem -העלפֿ "helf-" 'help'. The vowel change is unpredictable, and there is no way to tell from the infinitive whether a verb is weak or strong.