The article studies further broadening and sophistication of mastered lexico-grammatical material through use of modality and The Sequence of Tenses which helps students to produce more complex syntactic structures and enhance the speech act.
A. N. Spiridonov, K. V. Fedorov (2010) Interaction of lexical and grammatical aspects in foreign languages teaching (the beginner level). Journal of Mining Institute. Vol 187. p. 295.