The starting point of the analysis was the sentence regarded as isolated structural whole. In accordance with the theory of valence and grammatical dependence of Ulrich Engel, the verb occupies the central position and plays the principal role in the sentence), allowing places for compulsory and optional elements. Compulsory sentence elements are termed complements (’Erganzungen’). They differ from one another in form, function and meaning. Attention is given to the verbal complement (’Verbativerganzung’, in Ulrich Engel’s terminology). The analysis of instances studied in German and Serbo-Croatian has revealed that: 1 The verbal complement is almost exclusively realised by the infinitive, and the term ’infinitive complement’ is suggested for it; 2 Verbs requiring such complement are in the majority of instances verbs of incomplete predication (’Neberverben’) — auxiliary verbs, modal verbs, verbs of modality, and a few others, e. g. verbs of modified meaning; 3 All the verbs which were studied have two or three valencies, in both languages. Comparison of the German verbs with their Serbo-Croatian equivalents revealed that their valencias are not always reciprocal. This is shown in the list of verbs requiring infinitive complement.
