The comparative analysis of complement clauses and infinitive clauses in Polish and French throw light on the sequence to, ze(by) P / ce que P introducing complement clauses in the two languages. The comparison demonstrates that in the face of 'ce' that is deleted or gramaticalised in French complement clauses, we have an attested introductor to1 in Polish which changes its own nature when it is accented. To1 becomes the demonstrative pronoun to2 (this), which can cause a dislocation of the sequence to, ze(by) P. The comparison shows also that these structures are affected by delections which are different according to the language (particulary the infinitive structures).