In this paper, we explored the phenomenon of noun-incorporation in the English language as a means of expanding or reducing verb valency. In section 2, we focused on a previous study of noun-incorporation and verb valency. In section 4 we presented our classification of English incorporation complexes which consists of five groups of verbs correlating to the incorporated actant type. Finally, we showed that incorporation of actants entails simple or complex reducing of verb valency which simplifies the syntactic structure of a sentence without adding complexity to its semantics.

Actually, the paragraph is taken from the conclusion, that's why I thought past would be more appropriate there. As for that clumsy phrase, I've realised that I missed the preposition of, so it should be "complex change of verb valency". Anyway, thank you for your help!

As Dawei suggests, the "complex change verb valency" part is the only part that gives me trouble. While I do not speak this jargon, his answer seems good. or maybe ... simple or complex changes to verb latency ... Was this you meaning? . You seem an expert at English? Yet you ask here? :) . In my field we do not publish in the past tense for describing the article. In section 4 the text presents. When you write it, section 4 presents. A year later, the text is unchanged, so section 4 presents. Not presented. Describing the paper uses the present. Describing the work uses the past . . I understand that this may be different in your field. These are publishing conventions, noticeably different from field to field. They differ as much, maybe, as citation styles differ. . So in this paper, we explore, or explored, depending on whether you are describing the work, or the paper. section 2 we focus - as it is the paper you describe, not the work. Finally we showed - could be the work, past, already done,or the paper, presnt. .