for regular 3S verbs. Examples of irregular verbs and their principal parts Regular verbs Most verbs are regular enough that all forms can be derived directly from the infinitive. For example, the verb love derives all its forms systematically (love, loved, loving, has loved, loves), and since these can all be deduced from the basic form (the citation, dictionary, or lexicographic form, which in English is the bare infinitive), no other principal parts have to be learned. With irregular verbs like the verb sing, on the other hand, the forms sang and (have) sung cannot be deduced, so the learner of English must memorize three principal parts, sing–sang–(have) sung. The present 3S (he/she/it) is derived from the infinitive+'s' with the exception of verbs ending in a single -o, or ending in -s, -x, -z or the digraphs -sh, -ch, in which case it is derived from 'infinitive+es'. With three irregular verbs (and their derivatives) the 3S has to be learnt independently (e.g. has, does, undoes, redoes). Highly irregular verbs There are three verbs (and their derivatives) were three principal parts are insufficient to conjugate them fully having an irregular third person singular form in the present tense (in spelling and/or pronunciation). To be The verb "to be" is completely irregular having seven separate forms. German The situation in German is very similar to English. Regular verbs require no memorizing of principal parts, since all forms can be deduced from the infinitive. However, some uncertainty may exist as to the choice of the perfect auxiliary, which could be haben ('to have') or sein ('to be'). This can be solved by memorizing the infinitive with the third-person singular perfect tense, which some teachers recommend. tanzen - er hat getanzt Strong verbs and irregular weak verbs are more complicated. As in English, these verbs are usually memorized by means of three principal parts: infinitive – third-person singular past tense – third-person singular perfect tense. singen - sang - gesungen ('to sing' - a typical strong verb) bringen - brachte - gebracht ('to bring' - an irregular weak verb) However, in order to deduce the full paradigm, learners must also know the third-person singular present and the third-person singular past subjunctive, which involve some peculiarities. A small number of verbs have other irregularities, most of which are limited to the forms of the present tense. Icelandic There are four types of principal parts in