or "why?") usually occur at the beginning of the sentence, while those replacing arguments ("who?", "what?", etc.) often stay in the position of the replaced word. However, they can be fronted as well for the purpose of discourse-specific linking. Thus, a fronted šebi might be translated as "Which...?" instead of "What...?". Other interrogative pronouns include: dice ("how much?") didiyu ("which?") didur ("how?") łina-s ("why?"), this seems to be the genitive 1 form of the non-human oblique interrogative pronoun nā ("where?"), stem na- neti ("when?") šidā ("why?") šomo ("how many?") Verbs Tsez has a rich verbal morphology with many categories. Despite the great variety in conjugation, the only truly irregular verb is "to be" with some forms being yoł (present), ānu (present negative), zow- (past), etc. There are 4 morphological groups, according to the final phoneme of the stem: The first group ends in a consonant, the second in i, the third in -u and the fourth group contains the verbs with the variable ending -d (before a vowel) / -y (elsewhere). Tense-aspect-mood There are five tense forms in the indicative mood, shown in the following table with examples for verbs with vocalic and consonantal stem endings. The past forms make an evidentiality distinction. In interrogative sentences (English "wh-questions"), the past witnessed suffix is -ā instead of -s(i). In yes-no questions, the finite verb receives the additional ending -ā, except for the past witnessed form, which receives the ending -iyā (after consonants) or -yā (after vowels). Of the two different future tenses, the definite one bears the connotation of being wanted by the speaker ("I want and I will...") and is only used with the first person, while the indefinite one (simply "will") tends to be used with second and third. Other moods are formed as follows: The imperative has no suffix for intransitive verbs (e.g. -ikʼi! "go!") and the suffix -o for transitive verbs (e.g. tʼetʼr-o! "read!"); the verb is usually put in the first position in the phrase then. The optative adds a -ƛ to the imperative form, e.g. tʼetʼr-o-ƛ! ("let him read!"). There is also a great variety of analytical forms for verbs often exhibiting aspectual meaning: emphatic future = infinitive + "to be" (present tense); e.g. -ikʼ-a yoł ("shall go") continuous aspect = imperfect gerund + "to be" (in its appropriate tense-aspect form); e.g. -ikʼi-x zow-si ("was going") perfective aspect = perfect gerund + "to be"; e.g.